IPS Research Meeting 2011 February 25 and 26 - Institute of Physics...

IPS Research Meeting 2011

February 25 and 26

Institute of Physics Singapore

Conference Program

Foreword

Dear fellow Physicists,

We would like to thank all of you for coming to the second research meeting of theInstitude of Physics Singapore. Regular meetings have been important events in thecalendar of numerous physical societies around the world. These meetings are greatopportunities for members of the physics community to network and discuss scientificideas and exchange useful information. In many countries, some of the most importantdiscoveries were delivered during these meetings. That is the reason many of us joinmeetings of the American or European Physical societies. However we do have a strongand growing research community in physical sciences here in Singapore itself. Let usstrengthen the ties, and discover what exciting work is done in the neighboring lab orinstitute, and connect to the next generation!

The talks in this year’s meeting cover the wide range of research topics that your physicscolleagues in Singapore work on: from Solid state physics and material science, Nanoscience, and Biophysics over to Atomic, Molecular and Optical Physics, Ion beam tech-nology, reaching to more upstream topics like Quantum information, Astrophysics andeven Dark Energy. From the experience we had in our last meeting in 2009, we restrictedthe number of talks in favour of poster presentations, since this really encourages interac-tion with your fellow researchers. So take the time to browse through all the posters andinteract with the presenters. A special thanks goes to our junior researchers who joinedwith their research projects into our poster session as well: Keep an eye on the nextgeneration of researchers, and include them in the physics community here in Singapore!

In conjunction with this year’s meeting, we have also arranged an Education workshopon afternoon of 25 Feb 2011. We are indeed fortunate that Mdm Low Khah Gek,Director, Curriculum Planning and Development, Ministry of education has agreed tobe our Guest-of-Honor for the event. Also, Prof. Lui Pao Chuen, Advisor to the NationalResearch Foundation will be delivering the plenary talk at the workshop.

The organizing committee has worked hard to ensure a compact and succinct program.On behalf of the Institute of Physics Singapore (IPS), we would like to thank everybodywho has contributed in one way or another to this event: principal (Dr. Hang KimHoo), staff and students of the National University of Singapore High School, membersof the local organizing committee, especially Markus Baden. For logistics support, wespecifically thank staff of NUS Science Faculty and the Centre for Quantum Technologies,and all voluntary helpers who have in one way or other contributed to the organizationof this event.and. Last but not least, this is your conference: So a big thank you to allspeakers and contributors to the poster sessions!

Christian Kurtsiefer, Chairman, Local Organizing Committee

Leong-Chuan Kwek, President, IPS

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Contents

1. Schedule 3

2. Keynotes 4

3. Talks 53.1. General Interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.2. Nano Science . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.3. Biophysics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.4. Theoretical Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143.5. Atomic, Molecular & Optical Physics . . . . . . . . . . . . . . . . . . . . . 163.6. Interdisciplinary Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4. Posters 23

Author List 41

A. Physics Education Seminar 44

B. Seminar Room Location 45

C. Map of the Concourse 46

1. Schedule

Friday, February 25

8.00 AM Registration9.00 AM Opening Address, Auditorium9.10 AM Apples, Nails, Heart attacks and Nuclear particle beams, Auditorium

10.00 AM Information causality as a physical principle, Auditorium

10.40 AM Coffee/Tea Break

11.00 AM General InterestSeminar Room 1

Nano ScienceSeminar Room 2B

BiophysicsSeminar Room 2A

12.40 PM Lunch

2.00 PM Opening PhysicsEducation SeminarAuditorium

Poster SessionConcourse

2.50 PM Coffee/Tea Break

3.10 PM Education SessionSee appendix A

Theoretical PhysicsTheatreatte

4.30 PM Education ForumAuditorium

Saturday, February 26

9.00 AM Nanopore Biosensing and Sequencing, Auditorium

9.40 AM Poster Session, Concourse10.20 AM Coffee/Tea Break

10.40 AM Atomic, Molecular &Optical PhysicsSeminar Room 1

Interdisciplinary PhysicsSeminar Room 2B

12.40 PM Closing Address and IPS Poster Award, Auditorium

12.45 PM Lunch / End of Meeting

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2. Keynotes

Apples, Nails, Heart attacks and Nuclear particle beamsFrank Watt, CIBA / NUS

Friday 9.10 AM, Auditorium

Many developments in physics have led to interesting applications in other scientificdisciplines. In this talk I will describe the use of nuclear particle beams in elucidating apossible new risk factor in atherosclerosis (coronary heart disease).

Information causality as a physical principleValerio Scarani, CQT / NUS

Friday 10.00 AM, Auditorium

Quantum mechanics is usually defined by describing its formalism: physical systemsare described in Hilbert spaces, with some rules. In the past decades, several schoolstried to start from sets of reasonable axioms: they ended up identifying a large setof ”generalized probabilistic theories” but failed to single out quantum physics amongthose. In 1994, Popescu and Rohrlich showed that the possibility of ”non-locality with-out signaling” is also not enough to define quantum physics: the set of no-signalingprobabilities is strictly larger than the set of probabilities that can be obtained by mea-suring quantum systems. In the past few years, it has been an open problem in quantuminformation science to find criteria that would allow ruling out ”more-than-quantum”probability points. In this talk, I shall review the pioneering works, then I shall presentour contribution: the principle of ”information causality” [M. Pawlowski et al, Nature461, 1101 (2009)]. I shall show how, by enforcing this principle, one comes very close toidentifying the quantum set.

Nanopore Biosensing and Sequencing: Towards Personalized MedicineXiong Qihua, NTU

Saturday 9.00 AM, Auditorium

To be announced

3. Talks

3.1. General Interest

This session will be hel on Friday, February 25, from 11.00 AM to 12.40 PM. The venueis Seminar Room 1. Time allocated for each talks is 20 minutes, including questions.

Carbon Nanotubes Based Scaffolds for Assembly of Nanoparticles andLaser-Induced Micro-ActuatorsChornghaur Sow*

Friday 11.00 AM, Seminar Room 1

We have developed a simple focused laser pruning technique to fabricate two andthree-dimensional (3D) microstructures made of aligned array of multi-walled CarbonNanotubes (MWCNTs). The interaction of the focused laser beam with the MWCNTsalso resulted in the emission of intense light enabling the MWCNTs as localized heatand light source. Using this focused laser beam nanofabrication technique, we created awide variety of 3D microstructures. These microstructures could be used for the selectiveassembly of nanoparticles (ZnO) or quantum dots (QDs) en route to unique functionalhybrid nanomaterial systems. During the assembly of QDs onto the MWCNT, thealigned array of MWCNTs scaffold was found to be effective NanoSieve that could sortout QDs with a very small size difference ( 1nm). In this case, a droplet of solutioncomprising QDs of different sizes was placed on aligned array of MWCNTs. During thedeposition, the smaller QDs were found to assemble deeper into the MWCNTs. TheseQDs could be revealed after part of the MWCNTs was removed by laser pruning. Fluo-rescence microscopy showed multi-colored MWCNT microstructures due to preferentialdecoration of these QDs with difference sizes. In addition, the same focused laser beamwas able to cause mechanical actuation of MWCNTs microstructures after they are fab-ricated. Such behavior was exploited in creating simple micro-actuators comprising themicrostructures made of MWCNTs. This technique is convenient and effective, and haspotential applications in the fabrication of unique devices.

Superconducting atom chipBo Zhang*, Rainer Dumke


An atom chip is a device to manipulate the neutral atoms through inhomogeneousmagnetic fields, which are generated by the current-carrying microstructures integratedon the solid-state surface. The atom chips are widely used for the atomic interferometry,quantum computers and quantum information. However, the magnetic field fluctuationsdue to the Johnson noise may lead to atom loss and decoherence in the proximity of thecold atoms to the chip surface. Superconducting chips are proposed as a promising wayto significantly reduce the Johnson noise due to the small resistivity. We demonstrateda novel trap for neutral atoms employing the average magnetic field carried by vortices

trapped in type II superconductors. The vortices are induced by external magnetic fieldsor transport currents. We study the both cases. We use Bean’s critical state methodto compute the supercurrents, hence obtain the magnetic field distribution by Biot-Savart theorem. These inhomogeneous magnetic field carried by the vortices are studiedin detail and compare to those generated by multiple normally conducting wires withtransport currents. Versatile trapping potentials can be obtained with various vortexpatterns generated by different loading-field and transport-current sequences. Thesevortex-based traps may further reduce the noise coming from the power source due tothe absent of the transport-currents in operation. Our work also shows that these vortex-based traps provide a new platform for atom-optics and applications in cold quantumgases.

Tailoring Graphene properties through edge engineering, intercalation and stackingZe Xiang Shen*, Da Zhan


Graphene exhibits many exciting properties, such as anomalously quantized Hall ef-fects, massless Dirac-Fermions like charge carrier, existence of a minimum conductivity,which make it promising material for the future nano-electronic devices. All these prop-erties are originated from its unique band structure whose conical valence and conduc-tion bands meet at the Dirac point in Brillouin zone. In this talk, I will present ourresults of graphene study: new understanding on graphene intercalation, and propertiesof folded and mis-oriented graphenes. With the availability of few-layer graphene, weshed new light on the mechanism of intercalation of graphite which is not possible before.Folded graphene sheets exhibit two-dimensional Dirac-like (single layer graphene-like)character of electronic states and with reduction of Fermi velocity. For applicationsin nano-electronic devices and energy harvesting, opening of the band gap is needed.On the other hand, many of the unique properties of graphene are accorded to that ofsingle layer graphene (SLG). But it is very difficult to fabricate large single crystallineSLG samples for practical applications. It would be most desirable to modify few-layergraphene (FLG) samples so that they have similar properties as that of SLG. I will alsopresent our results in modifying graphene for various applications, including modifyingedge chirality, hydrogenation, and studies of graphene with mis-oriented layers.

Astronomy in SingaporePhil Chan*

Friday 12.00 PM, Seminar Room 1

Local Astronomy has generated huge interest amongst students at all levels and alsothe public. We will survey the annual IPS Astronomy activities namely, IPS AstronomyCompetitions for Secondary Schools (NYP, 14th year), IPS Astronomy Overseas Retreat(Malaysia& Indonesia) for the public (NYP, 18th year) and the 12 (+ 2) local Astro-Observatories. We will also briefly mention the other local astro groups: CB Paul

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Memorial Competition (ACJC, 33 years), SingAstro Forum, TASOS and Annual NTU-NUS Astro-Challenge. There are 6 local Astro-Vendors. Finally, we will have a glimpseof some Astro-physics research and JC/Poly/Sec Astronomy projects done locally.

A Different Look at Dark Energy and the Time Variation of Fundamental ConstantsMarvin Weinstein*

Friday 12.20 PM, Seminar Room 1

In this talk I will give a short introduction to a recent paper which took a differentlook at dark energy and the time variation of fundamental constants. The topic will bepresented in a format suitable for a non-specialist audience.

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3.2. Nano Science

This session will be hel on Friday, February 25, from 11.00 AM to 12.40 PM. The venueis Seminar Room 2B. Time allocated for each talks is 20 minutes, including questions.

Multi-Paradigm Simulations at the Nanoscale: Methodology and Applications toFunctional Carbon MaterialsHaibin Su*

Friday 11.00 AM, Seminar Room 2B

Multiparadigm methods to span the scales from quantum mechanics to practical issuesof functional nanoassembly and nanofabrication are enabling first principles predictionsto guide and complement the experimental developments by designing and optimizingcomputationally the materials compositions and structures to assemble nanoscale sys-tems with the requisite properties. In this talk, we employ multi-paradigm approachesto investigate functional carbon materials with versatile character, including fullerene,carbon nanotube (CNT), graphene, and related hybrid structures, which have alreadycreated an enormous impact on next generation nano devices. The topics will coverthe reaction dynamics of C60 dimerization and the more challenging complex tubularfullerene formation process in the peapod structures; the computational design of a newgeneration of peapod nano-oscillators, the predicted magnetic state in NanoBuds; andopto-electronic properties of graphene nanoribbons.

Electrically Adjustable, Super Adhesive Force of Superhydrophobic Aligned MnO2Nanotube MembraneXiaodan Zhao, Xiangyang Liu*


We report a superhydrophobic membrane of MnO2 nanotube arrays on which a waterdroplet can be immobilized by application of a small DC bias, despite of its large contactangle. For a 3 μL water droplet, the measured adhesive force increases monotonicallywith increasing negative voltage, reaching a maximum of 130 μN at 22 V, 25 timeshigher than the original value. It follows that the nearly spherical water droplet canbe controllably pinned on the substrate, even if the substrate is turned upside down.Moreover, the electrically adjustable adhesion is strongly polarity-dependent; only a five-fold increase is found when a positive bias of 22 V is applied. This remarkable electricallycontrolled adhesive property is ascribed to the change of contact geometries between thewater droplet and MnO2 nanotube arrays, on which water droplets exhibit differentcontinuities of three-phase contact line (TCL). As the modulation in this manner is insitu, fast, efficient and environment-friendly, this kind of smart material with electricallyadjustable adhesive property is expected to find various applications in biotechnologyand in lab-on-chip devices.

Strain effects on catalytic and hydrogen storage properties of metal-functionalized

grapheneMiao Zhou*, Chun Zhang, Yuan Ping Feng


Recently, there has been a surge in studying strain effects in graphene. In this pre-sentation, we will first report a first-principles investigation aiming at controlling thestabilization and catalytic activity of metal nanoclusters supported on graphene via tun-ing the mechanical strain in graphene. It is shown that a relatively small tensile strain(10Following that, we will also present some interesting results on strain-engineered hy-drogen storage capabilities of metal-decorated graphene. We will show a tensile strainof 10

Eigenvibrations and mechanical properties of nanoparticlesJing Ya Sun, Zhi Kui Wang, Vanessa Li Zhang, Hock Siah Lim, Ser Choon Ng, MengHau Kuok*

Friday 12.00 PM, Seminar Room 2B

Because of their wide ranging applications, nanoparticles have attracted much researchinterest in diverse areas such as catalysis, optics, biomedicine, phototherapy, and colori-metric detection. Information on the eigenvibrations of nanoparticles is important as it,among other things, allows the calculation of their thermal and mechanical propertiessuch as the specific heat due to phonons. This presentation will report on Brillouin lightscattering studies of the eigenvibrations and mechanical properties of particles, such asnanospheres, nanocubes, hollow nanospheres, and core-shell nanoparticles. The confinedacoustic modes of the nanostructures observed show significantly different features fromthose of the corresponding bulk material. Finite element simulations of the vibrationalmodes have also been carried out to identify and elucidate the nature of the observedeigenmodes.

Improved Hydrophobicity of Carbon Nanotube Arrays with MicropatterningSharon Xiaodai Lim, Chorng Haur Sow*

Friday 12.20 PM, Seminar Room 2B

The hydrophobicity of vertically aligned multiwalled carbon nanotubes (MWCNTs)was improved through the creation of a parallel array of microwalls via a laser pruningtechnique. Changes to the hydrophobic nature of the patterned MWCNTs due to ar-tificially induced roughness through variations in both the widths of the walls and thedistance between adjacent walls, channel width, were investigated. The sample becamemore hydrophobic whenever water droplets landed on one microwall 7 or 13 μm in width.However, when a droplet bridged two microwalls, the surface became less hydrophobic.The optimal superhydrophobic MWCNT surface corresponded to a parallel array of mi-crowalls with a width of 13 μm and a channel width of 50 μm. Such findings couldpossibly serve as value-add for further developments in the creation of water-repelling

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CNT surfaces via micropatterning.

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3.3. Biophysics

This session will be hel on Friday, February 25, from 11.00 AM to 12.40 PM. The venueis Seminar Room 2A. Time allocated for each talks is 20 minutes, including questions.

Sustained quantum coherence and entanglement in the avian compassErik Gauger, Elisabeth Rieper*, Simon Benjamin, John Morton, Vlatko Vedral

Friday 11.00 AM, Seminar Room 2A

In artificial systems, quantum superposition and entanglement typically decay rapidlyunless cryogenic temperatures are used. Could life have evolved to exploit such delicatephenomena? Certain migratory birds have the ability to sense very subtle variations inthe Earth’s magnetic field. Here we apply quantum information theory and the widelyaccepted ‘radical pair’ model to analyse recent experimental observations of the aviancompass. We find that superposition and entanglement are sustained in this livingsystem for at least tens of microseconds, exceeding the durations achieved in the bestcomparable man-made molecular systems. This conclusion is starkly at variance withthe view that life is too ‘warm and wet’ for such quantum phenomena to endure. [Phys.Rev. Lett. 106, 040503 (2011) ]

Bio-mimic nature structural colors using silk fibroinYingying Diao*


Inspired by fine structures and excellent optical properties of opals, colours, we suc-cessfully mimicked nature structural colours using biocompatible material: silk fibroin.Through a simple templating approach, three-dimensional (3D) face centre cubic (FCC)photonic crystals made of air spheres in silk fibroin were obtained. By precisely control-ling the lattice constants of the inverse opals, silk fibroin films with diversified colourswere achieved. Furthermore, according to theoretical modelling, two photonic band gaps(PBG) existed along the Γ-L direction in the first Brillouin zone of the silk fibroin in-verse opals. Either of which can produce iridescent structural colours. Two reflectionpeaks were identified in the angle-resolved reflectance spectra of the silk fibroin inverseopals, which proved the existence of these two photonic band gaps. Dispersion relationsbetween the reflection peaks’ positions and the wave vectors of the incident light wereacquired from the measured spectra. The number, centre frequencies and angular rangeof the measured spectral peaks agreed well with the simulated photonic bands structure.

EC1-5 partial unfolding and mechanical stabilityFei Wu*, Ruchuan Liu*


In this talk partial unfolding and mechanical stability of E-cadherin extracellulardomain1-5(EC1-5) single molecule studied by AFM will be introduced. Cadherins are a

class of transmenbrane proteins which play important roles in cell-cell adhesion. Theseproteins share the similar molecular structure which contains 3 regions: the extracellularregion which can bind to other cadherin molecules to form cadherin-cadherin bindingbond, the transmembrane region, and the cytoplasmic region which binding to cytoskele-ton in the cells. Among these 3 regions, extracellular region plays the dominant role incadherin-cadherin interaction in tissues. E-cadherin is named for it exists in epithelialtissue and dominates the cell-cell interaction in this tissue. Its extracellular region con-tains five domains folding separately and each domain contains 7 β-sheets. There are 3Ca2+ binding on the linkers between each domain. These Ca2+ not only bind to thesites on linkers, but also bind to the sites in each domains. Various of reported work onboth experiment and simulation show that this binding could stabilize the structure ofcadherin extracellular domains. Moreover, studies of cadherins also show that the Ca2+could stabilize the cadherin-cadherin binding interaction. Nevertheless, the model of thisinteraction is still controversial. In addition, the simulation suggest that the extracellulardomains may experience some stable intermediate states during unfolding which needbig forces to overcome the energy barriers, however, whether these intermediate statesreally exist in cadherin molecules unfolding and whether they can affect the cadherin-cadherin interaction are still unknown. We studied EC1-5 and show the partial unfoldingevents observed in E-cadherin single molecule pulling experiment based on AFM. Thesepartial unfolding events may provide some stable intermediate states which could playan important role in cadherin-cadherin interaction. In addition, we perform the pullingexperiment in different environments and observed different unfolding behaviors. There-fore the comparison of the unfolding behavior of single molecule and unbinding force ofcadherin-cadherin interaction in these environments may provide a method to establishthe connection between the molecule structure and interaction, furthermore, may ex-plain how does intermediate states affect the cadherin-cadherin binding and propose amore reasonable model for the cadherin-cadherin interaction.

DNA stiffening and folding by Pseudomonas aeruginosa nucleoid-associated proteinMvaT and MvaURicksen Winardhi, Jie Yan*

Friday 12.00 PM, Seminar Room 2A

The advent of single molecule techniques has brought a new era in studying DNA-protein interactions. In this particular talk, we will present about the use of transversemagnetic tweezers and atomic force microscope in studying DNA-protein interaction.Magnetic tweezers renders the capability to manipulate a single DNA and probe itsmechanical behavior. Polymer theory has been developed to utilize this tool to studyprotein binding properties. In addition, atomic force microscope is used to visualize thesingle molecular complexes. These physical tools provides direct means and real timeacquisition of DNA and protein bindings. We will use these tools to study a global generegulator in Pseudomonas aeruginosa, called MvaT and MvaU, which plays a major rolein the microorganism. The results provided by these single molecule techniques pro-

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vides indispensable insights into unlocking the physical mechanism of DNA and proteinbinding properties.

Kinetic simulations of tension-induced DNA strand-unpeeling transitionYuanyuan Qu*, Hongxia Fu, Jie Yan*

Friday 12.20 PM, Seminar Room 2A

Sequence- and salt- dependent kinetic simulation assuming strand-unpeeling from B-DNA using the Gillespie’s stochastic kinetics simulation algorithm was performed forDNA fragments of a few hundred base pairs. Similar to DNA unzipping experiments,sequence-dependent energy barriers resulted stepwise extension changes were observedduring the transition. The simulations were compared with recent single-molecule studiesof overstretching transition of the same DNAs occurring at around 65 pN. The resultsquantitatively reproduced the dynamics of overstretching transition of the same DNAsunder conditions when overstretching led to strand separation, and were distinct fromthat when the transition led to a double-stranded overstretched DNA called “S-DNA”through the B-S transition pathway. We conclude that the strand separation transitionpathway was a strand-unpeeling transition from the two free ends of DNA. Further, ourresults suggest that the B-S transition pathway does not involve base-pair separation.

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3.4. Theoretical Physics

This session will be hel on Friday, February 25, from 03.10 PM to 04.50 PM. The venueis Theatreatte. Time allocated for each talks is 20 minutes, including questions.

Quantum Bell Inequalities from Macroscopic LocalityTzyh Haur Yang*, Valerio Scarani, Miguel Navascues, Lana Sheridan

Friday 03.10 PM, Theatreatte

We propose a method to generate analytical quantum Bell inequalities based on theprinciple of Macroscopic Locality. By imposing locality over binary processings of virtualmacroscopic intensities, we establish a correspondence between Bell inequalities andquantum Bell inequalities in bipartite scenarios with dichotomic observables. We discusshow to improve the latter approximation and how to extend our ideas to scenarios withmore than two outcomes per setting.

CGLMP4 as dimension witnessYu Cai*, Valerio Scarani


The dimension of the Hilbert space is a useful resource in quantum information sci-ence. Given a black box description of the statistics obtained from a bipartite experi-ment, Bell’s inequality reveal whether the same statistics could be reproduced by localhidden variable (LHV) model. It is found that Bell’s inequality could also manifestsomething about the dimension of Hilbert space that describes the system. More pre-cisely, higher dimension system could violate Bell’s inequality more than lower dimensionsystem could. In other words, for certain violation of Bell’s inequality, we could surelygive a lower bound for the dimension of the Hilbert space that describes the bipartitesystem. Here we shall present some results for CGLMP4 inequality, a variation of Bell’sinequality, acting as a dimension witness for ququad (four-level) systems, together withnumeric results and proposed experimental schemes.

Supersymmetric Surface Operators, Four-Manifold Theory and Invariants inVarious DimensionsMeng-Chwan Tan*


I will talk about my recent work in [arXiv:0912.4261] and [arXiv:1006.3313], regardingthe application of supersymmetric surface operators in a topologically-twisted N=2 pureSU(2) gauge theory, to the study of four-manifolds and topological invariants in two,three and four dimensions. I will first explain how elegant physical proofs of variousseminal theorems in four-manifold theory obtained by Ozsvath-Szabo and Taubes, canbe derived. I will then go on to explain how one can, via the underlying physics, arrive atmathematically-novel identities amongst the Gromov and singular Seiberg-Witten invari-

ants of symplectic four-manifolds, and furthermore, how these invariants can be relatedto the instanton and monopole Floer homologies of certain three-submanifolds. Last butnot least, I will present new and economical ways of deriving and understanding vari-ous important mathematical results concerning (1) knot homology groups from singularinstantons by Kronheimer-Mrowka; (2) monopole Floer homology by Kutluhan-Taubes;and (3) Seiberg-Witten theory on symplectic four-manifolds.

Precise Determination of Eigenvalues for the Spherical Linear PotentialSwee Ping Chia*


Because of asymptotic freedom behaviour, quark and antiquark in a tightly boundmesonic system behave like free particles, under the influence of a potential, whichcan be described, to a first approximation, by a linear potential. The Schroedingerequation for the linear potential can be reduced to the following dimensionless form: -U”+[L(L+1)/r*r+r]U=EU Numerical integration is performed using Runge-Kutta method.The present paper attempts to obtain, to a high degree of accuracy, the eigenvalues forthe spherical linear potential. Also presented is the behaviour of the eigenfunctions.

Development of fractal lattices and self-organized critical models in dimensionbetween 1 and 2Nguyen Huynh*


Since being introduced by Bak, Tang and Wiesenfeld, Self Organized Criticality (SOC)has been the most popular subject within Complexity. Fractal, on the other hand, is aparadigmatic example of generating complicated structures by iterating simple rules. Inthis talk, I will introduce a universal procedure of generating fractals and lattices usinggeometric arcs. The lattices possess different neighboring structures and their fractaldimension can be tuned between 1 and 2. SOC models, especially sandpile models, arethen studied on these lattices. Several interesting results on scaling laws, which aredifferent from those in regular lattices, are reported.

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3.5. Atomic, Molecular & Optical Physics

This session will be hel on Saturday, February 26, from 10.40 AM to 12.40 PM. The venueis Seminar Room 1. Time allocated for each talks is 20 minutes, including questions.

Improved detection efficiency using Raman RepumpingBoon Leng Chuah*, Nicholas Lewty, Murray Douglas Barrett

Saturday 10.40 AM, Seminar Room 1

Trapped ions are a promising tool towards the implementation quantum informationprocessing. At CQT, we work with Barium ions as the optical frequencies involved arefavourable for planned cavity QED experiments. However state detection in Barium isdifficult due to the lack of an available cycling transition. Here we demonstrate thathigh detection efficiency in 137Ba+ is possible in spite of this problem. Due to the largefine structure splitting in 137Ba+, a combination of Raman coupling between magneticsubstates of the D3/2 hyperfine states and resonant optical pumping leaves the —F =3, mF = 3 ¿ optically dark and relatively immune to off-resonant optical pumping. Allother states are strongly coupled to the upper P1/2 state. We report a state detectionefficiency of 88

Controllable coupling between superconducting qubitsJing Yan Haw*, Valerio Scarani*


Superconducting circuits are promising candidates for constructing qubits in quantumcomputer, in which the role of artificial atoms are played by superconducting qubits. Dueto the flexibility of the design and strong coupling strength, this new domain, which iscalled “Circuit Quantum Electrodynamics”, can in turn explore new regimes. One thathas attracted attention very recently is the ultrastrong coupling regime, which is beyondthe well-established Jaynes-Cummings model and has been realized experimentally. Inthis research project, we proposed a scheme to realize the controlled coupling betweensuperconducting qubits, namely the charge and flux qubits via a mechanical harmonicoscillator called nanomechanical resonator, which can be utilized for quantum informa-tion processing such as quantum gate operation and entanglement generation. Usinga general form of Jaynes-Cummings model in dispersive regime, which applies to bothrotating wave approximation (RWA) regime and ultrastrong coupling regime, we demon-strate and investigate the quantum gates operations and the entanglement propertiesbetween the qubits of our setup.

Superconducting Atom Chip - Trapping of Ultracold Atoms in the Remanent State

of Type-II SuperconductorChan Kin Sung*, Zhang Bo, Rainer Dumke


We have realized a novel magnetic trap for ultracold atoms based on the remanentstate in a high temperature superconducting micro-structure. Quantized magnetic fluxvortices trapped in the superconductor create inhomogeneous magnetic fields which arecombined with bias fields to form a magnetic trap. We demonstrate the control of crucialmagnetic trap parameters such as spatial positioning and flux vortex density trapped inthe superconductor. In addition, by making use of the hysteretic behavior of the rema-nent state of the type-II superconductor, different traps of flexible magnetic potentials forultra-cold atoms are demonstrated. Current progress is towards the measurement of theeffects of vortices in the superconductor on the coherence of the trapped atoms. Theseresults provide a feasibility study towards the future realization of quantum informa-tion processing and the interfacing of atomic quantum system and solid state quantumsystem.

Brillouin Studies of Phononic CrystalsHuihui Pan*, Vanessa Li Zhang, Zhi Kui Wang, Hock Siah Lim, Ser Choon Ng, MengHau Kuok*


Phononic crystals are a novel and interesting class of materials which enable thecontrol of the propagation of elastic waves (phonons). The elastic analog of photoniccrystals, they exhibit periodic variations of density and elastic property, resulting inphononic bandgaps which prevent acoustic waves with certain frequencies from propa-gating through them. Phononic crystals are thus of great fundamental scientific interestand show great promise in a wide variety of applications such as acoustic lasers, heat man-agement devices, and acoustic superlenses. Investigations into the acoustic dynamics ofphononic crystals, in the form of various nanostructured periodic arrays, are presented.In these studies, Brillouin light scattering, a powerful technique for probing acousticwaves in the gigahertz range, has been employed to measure the frequency bandgapstructures of these artificial crystals.

Large exchange bias after zero-field cooling from an unmagnetized stateBaomin Wang, Yong Liu*, Peng Ren, Bin Xia, Kaibin Ruan, Jiabao Yi, Jun Ding,Xiaoguang Li, Lan Wang*

Saturday 12.00 PM, Seminar Room 1

Exchange bias (EB) is usually observed in systems with interface between differentmagnetic phases after field cooling. In this Letter, we report an unexpected finding thata large EB can be realized in Ni-Mn-In bulk alloys after zero-field cooling from an un-magnetized state. We propose that the size of superparamagnetic domains in the alloys

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can grow up under external magnetic fields, which induces a transition from a superspinglass to a superferromagnetic (SFM) state. The SFM unidirectional anisotropy, whichis the origin of EB effect, can be created at the newly formed SFM-antiferromganticinterface during the initial magnetizing process.

Negative refraction processes in matter-wave opticsMartial Ducloy*

Saturday 12.20 PM, Seminar Room 1

I will discuss about the generalisation to matter-wave optics of the functions previ-ously demonstrated in light optics. In particular the way of devising media exhibitingnegative refraction (“Negative Index Media”, NIM) for matter waves will be presented,and the distinct features between NIM’s for atom-wave optics and electron-wave opticsemphasized. A few characteristic applications like “meta-lenses” for atoms, time-reversalof matter waves allowing for wave-packet shortening, can be deduced.

References J. Baudon et al, “Negative-index media for matter-wave optics”, Phys.Rev. Lett. 102, 140403 (2009) M. Hamamda et al, “Dynamics of evanescent matterwaves in negative-index media”, J. Phys. B: At. Mol. Opt. Phys. 43, 215301 (2010) M.Hamamda et al, ”Time reversal in matter-wave optics”, The European Physical JournalD 61, 321 (2011) V. Klimov, J. Baudon, M. Ducloy, ”Comparative focusing of Maxwelland Dirac fields by negative refraction half-space”, submitted (2011)

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3.6. Interdisciplinary Physics

This session will be hel on Saturday, February 26, from 10.40 AM to 12.40 PM. The venueis Seminar Room 2B. Time allocated for each talks is 20 minutes, including questions.

Functional properties of nano/submicron sized Energy storage materialsM V Reddy*

Saturday 10.40 AM, Seminar Room 2B

Functional properties of nano/submicron sized Energy storage materials M V Reddy*and B V R Chowdari Department of Physics, National University of Singapore, Sin-gapore 117546 Lithium ion batteries are extensively used in the present-day portableelectronic gadgets like, cell phones, notebook computers, i-pads and video camcorders,medical industry as defibrillators, pace-makers etc, and in the aerospace industry for stor-ing photovoltaic-generated dc-electricity and hybrid electric vehicules (HEVs). Commer-cial lithium ion batteries use lithium cobalt oxide as the cathode (positive electrode) andgraphite as the anode (negative electrode) material. To replace LiCoO2, graphite, reducethe cost and improve safety, efforts have been made by researchers to find alternativematerials. Recently, nanostructure metal oxides have attracted as electrode materials forlithium ion batteries because of their chemical stability and high surface area leads facileLi-intercalation/de-intercalation process. In my talk i will discus introduction, princi-ples and preparation of electrode materials by various chemical and physical methods.Materials were well characterized by Rutherford backscattering spectroscopy, Rietveldrefinement X-ray diffraction, Raman spectroscopy, X-Ray photoelectron spectroscopy,X-ray absorption fine structure, Neutron diffraction, SEM, and HRTEM. Functionalproperties of the materials were evaluated by using various electro analytical techniquesand Li-ion transport studies were studied using impedance spectroscopy technique. I willthe role of materials physicists and chemists in basic understanding of energy storage ma-terials. *Corresponding author: Dr. M.V. Reddy, E-mail address: [email protected]; Tel.: +65-65162605; Fax: +65-67776126 References : (1) M. Armand and J. M. Taras-con, Nature, 451 (2008) 652-657. (2) M.V. Reddy, G.V. Subba Rao, B.V. R. Chowdari“Binary, ternary and complex oxides as anode materials for lithium batteries” Journalof Materials Chemistry (2011) (Review article) (3) M.V. Reddy, G.V. Subba Rao, B.V.R. Chowdari “Nano-(V1/2Sb1/2Sn)O4 as high performance anode material for Li-ionbatteries”. Journal of Materials Chemistry (2011) (DOI:10.1039/C0JMO4140H). (3)M.V. Reddy, Zhang Beichen, Li Jia’en Nicholette, Zhang Kaimeng and B. V. R. Chow-dari “Molten salt synthesis of Co3O4 as anode for lithium batteries” Electrochemical &Solid State Letters (2011 in press) (4) (a) A. Sakunthala, M. V. Reddy, S. Selvasekara-pandian, B.V.R. Chowdari, P. Christopher Selvin “Energy storage studies of bare anddoped vanadium pentoxide, (V1.95M0.05)O5, M = Nb, Ta for lithium ion batteries”Energy and Environmental Science (2011) (DOI:10.1039/C0EE00513D (b) A. Le Viet,M .V. Reddy, R. Jose, B. V. R. Chowdari and S. Ramakrishna“Electrospun NiobiumPentoxide Nanofiber Polymorphs for Rechargeable Lithium Ion batteries” Journal ofPhysical Chemistry C 114(2010)664-671 (5) (a) B. Varghese,. M.V. Reddy, Z. Yanwu,

C.S. Lit, G.V. SubbaRao, B.V.R. Chowdari, T.C. Hoong, A.T.S. Wee, C.T. Lim, C.H.Sow, Chemistry of Materials 20 (2008) 3360-3367 (b) M.V. Reddy, T. Yu, C.H. Sow,Z.X. Shen, C.T. Lim, G.V. Subba Rao, B.V.R. Chowdari Adv. Func. Mater. 17(2007)2792-2799. (c) M.V. Reddy, B. Pecquenard, P. Vinatier, C. Wannek, A. Levasseur, P.Moretto Nucl. Inst. & Meth. Phys. Res. B,246( 2006) 397.

Fewer Quintuple Layer Topological Insulator Bi2Se3 Nanoplatelets: PolyolSynthesis and Raman SpectroscopyQihua Xiong*, Jun Zhang, Zeping Peng, Ajay Soni, Yanyuan Zhao, Bo Peng


We report on Raman spectroscopy of few quintuple layer topological insulator BismuthSelenide (Bi2Se3) nanoplatelets (NPs), synthesized by a polyol method. The as-grownNPs exhibit excellent crystalline quality, hexagonal or truncated trigonal morphology,and flat surfaces down to a few quintuple layers. Both Stokes and anti-Stokes Ramanspectroscopy for the first time resolve all four optical phonon modes from individual NPsdown to 4 nm, where out-of-plane vibrational mode shows a few wavenumbers redshift asthe thickness decreases below 15 nm. This thickness-dependent redshift is tentativelyexplained by a “phonon softening” along the decreasing of effective restoring force dueto a decrease of van der Waals forces between adjacent layers. Quantitatively, we foundthat 2D phonon confinement model proposed by Faucet and Campbell cannot explain theredshift values and lineshape of mode, which can be described better by a Breit-Wigner-Fano resonance lineshape. Considerable broadening ( 17 cm-1 for 6 quintuple layers)especially for in-plane vibrational mode was identified, suggesting that the layer-to-layerstacking affects the intralayer bonding. Therefore, a significant reduction of phononlifetime of in-plane vibrational modes is probably due to an enhanced electron-phononcoupling in few quintuple layer regime.

Coded Aperture Imaging Technique for Investigation of Fusion Source SpatialDistribution in Plasma Focus DeviceAlireza Talebitaher*, Stuart Springham, Paul Shutler, Rawat Rajdeep, Lee Paul


The Coded Aperture Imaging (CAI) technique, which originally was developed forx-ray and γ-ray astronomy, has been applied to investigate the spatial distribution ofDD fusion in a 1.6 kJ Plasma Focus device with deuterium filling gas operated in itsneutron-optimized regime (1-3 E8). The mask has been fabricated with 20 20 pixels and57 square holes (14

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Electronic phase separation at the LaAlO3/SrTiO3 interfaceXiao Wang, Ariando*


There are many electronic and magnetic properties exhibited by complex oxides. Elec-tronic phase separation (EPS) is one of those, the presence of which can be linked toexotic behaviours, such as colossal magnetoresistance, metal–insulator transition andhigh-temperature superconductivity. A variety of new and unusual electronic phases atthe interfaces between complex oxides, in particular between two non-magnetic insulatorsLaAlO3 and SrTiO3, have stimulated the oxide community. However, no EPS has beenobserved in this system despite a theoretical prediction. Here, we report an EPS stateat the LaAlO3/SrTiO3 interface, where the interface charges are separated into regionsof a quasi-two-dimensional electron gas, a ferromagnetic phase, which persists aboveroom temperature, and a (superconductor like) diamagnetic/paramagnetic phase below60 K. The EPS is due to the selective occupancy (in the form of 2D-nanoscopic metallicdroplets) of interface sub-bands of the nearly degenerate Ti orbital in the SrTiO3. Theobservation of this EPS demonstrates the electronic and magnetic phenomena that canemerge at the interface between complex oxides mediated by the Ti orbital.

Plasma Focus: Simple High Energy Density Pulsed Plasma Device with RichPhysics and Vast PossibilitiesRajdeep Singh Rawat*

Saturday 12.00 PM, Seminar Room 2B

The plasma focus device is an alternative magnetic fusion device where a fast capaci-tor bank is discharged through the coaxial electrode assembly generating a super-sonicplasma whose dynamics is essentially controlled by very high pulsed discharge current.The short-lived plasma is electromagnetically compressed in hot and dense pinch plasmacolumn on ns time scale with generation of multiple radiations such as EUV, soft andhard x-rays, relativistic electrons, high energy ions and even fusion neutrons (if oper-ated with deuterium). The physics of this magnetohydrodynamically controlled fusionplasma device is quite complex and hasn’t been understood completely yet. The mulitpleradiations from this device however open up vast range of possible applications of thisdevice which will be disucssed in the IPS meeting.

Silicon solar cells by one step low-frequency high-density plasma processingShuyan Xu*

Saturday 12.20 PM, Seminar Room 2B

It is well known that plasma is a unique tool for material processing. There hasbeen a great deal of interest in high-density, low-temperature plasma sources for variousapplications. Inductively coupled plasma (ICP!)sources featuring high ion densities andlow plasma potentials have proved to be very efficient in the generation of large-area and

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large-volume plasmas for fabrication of unique nanostructures, synthesis, and processingof advanced materials and ultrafine selective etching of semiconductor wafers. In thistalk I will focus on the application of this method to silicon solar cells

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4. Posters

Posters will be presented in two sessions. One session takes place Friday, February 25,from 2 PM to 2.50 PM. The other session takes place Saturday, February 26, from 9.40AM to 10.20 AM. The venue for both sessions is the concourse. There, posters will begrouped in several booths, each booth containing four panels. For an overview of theconcourse please refer to the map in Appendix C.

All presenters are kindly asked to put up their posters as soon as possible and onlytake them down after the conference. Doing so will offer all participants the chance toexplore the posters during the conference breaks.

In particular there is no need for presenters of the first poster session to take downtheir posters in order to make room for the posters of the second sessions. There isenough room for posters of both sessions.

Effect of sp3-hybridized defects on the oscillatory behaviour of carbon nanotubeoscillatorsGuo Taiyu*, Ding Weixi Tony

Friday 2 PM, Concourse, Both No. 1, Panel A1

The oscillatory behaviors of carbon nanotube oscillators containing sp3-hybridizeddefects formed by hydrogen adsorption were investigated by molecular dynamics simu-lations. It was found that the presence of these defects significantly affects the kineticand potential energies of the systems, which in turn affects their oscillation periodsand frequencies. The defect-free oscillator is the most stable, followed by those withsp3-hybridized defects arranged in a ring around the outer nanotube, and oscillatorscontaining sp3-hybridized defects in rows along the nanotube are, however, the leaststable. The cause of the defect-induced oscillation decay lies in the deformations anddistortions incurred by the sp2 to sp3 bonding transition due to the adsorption of hy-drogen on the surface of the oscillators. We also studied the oscillation characteristicsof oscillators containing sp3-hybridized Stone-Wales defects. Our simulations show thatit is possible to control and tune the motion of the inner nanotube by introducing de-fects on the outer nanotube, indicating that our nanotube system has the potential fornano-mechanical operations as well as to function as a variety of nano-machines such asa nano-switch.

Characterization of nano-ZnCo2O4 material prepared by Molten Salt Method as ananode for Lithium Ion Batteries.Kenrick Koh, Ying Wei Tang, Yeow Chong Goh, M.V. Reddy*, B V R Chowdari, HockLeong Goh


Lithium ion batteries are one of the most promising technologies today, with potentialuses in everything ranging from handphones to hybrid vehicles. Commercially produced

Li-ion batteries today suffer relatively low cyclability and theoretical capacity of 372mAh/g as it uses graphite as the anode material. ZnCo2O4 has a high theoreticalcapacity ( 1000 mAh/g), thus we attempted to prepare single nano phase ZnCo2O4by using simple Molten Salt Method. Nano- ZnCo2O4 was synthesized using 0.88MLiNO3:0.12M LiCl molten salt at low temperature 280°C, for 30 min or 3h in air. Theeffects of Zn-sulphate, Co-sulphate, hydroxide salt combinations and surfactant on mor-phology and crystal structure of the ZnCo2O4 anode materials were studied. Character-ization of Nanopowders (ZnCo2O4) were achieved by Rietveld refined X-Ray Diffraction(XRD), Scanning Electron Microscopy (SEM), Density and BET surface area methods.Nanopowders (ZnCo2O4) showed single phase materials, and the range of surface areawas 5 to 32 m2/g. Evaluation of lithium batteries performances (anodic) were carriedout via Cyclic Voltammetry (CV), Galvanostatic Cycling and Impedance Spectroscopytechnique. Electrodes were fabricated using doctor blade technique for Li-cycling stud-ies. CV studies show main anodic peaks to occur at 1.7V and 2.2V, and cathodic peakat 0.75V. High and stable capacity of 950 mAh/g was observed at the end of 40 cy-cles for nano-ZnCo2O4 which was prepared using Zn-sulphate and Co-hydroxide source,when cycled with current rate of 60 mA/g and voltage range of 0.05V - 3.0V. The ob-served reaction mechanisms, cycling, rate capabilities studies and studies on surfactantassisted-ZnCo2O4 are discussed.

Photoresponse of CdSe nanorod functionalized grapheneShouheng Xu, Zongyou Yin, Hong Li, Qing Zhang*, Hua Zhang*


Since graphene, a mono-layer of carbon atoms organized in a honey-comb structure,was first isolated in 2004 [1], intensive research work has been carried out to study itselectrical and magnetic[2-8] properties. However, due to zero-band gap nature of the ma-terial, intrinsic clean graphene is expected to show insignificant photo responses. Onetechnique to make graphene photo sensitive is to produce an sizeable bandgap throughband gap engineering, i.e. graphene oxide reduction [9], graphene nano-ribbons[10-12],chemical doping[13]. An alternative way to make graphene photo-responsive is throughdecorating graphene with photo-sensitive materials. CdSe is a commonly used photosensitive inorganic material under visible light. To our knowledge, CdSe nanorod func-tionalized graphene has not been systematically investigated in terms of the photore-sponse. In this talk, we report on photoresponses from CdSe nanorod functionalizedgraphene.

Under light exposure, a significant decrease in the graphene channel conductance isobserved. The phenomenon is attributed to unique charge transfer between graphene andCdSe nanorods. When large amount of excess carriers are generated in CdSe nanorods,they could transfer to graphene and result in significant tuning of carrier density.As wellas its electrical performances. References

1. K.S.Novoselov, et al., Electric Field Effect in Atomically Thin Carbon Films. Sci-ence, 2004. 306: p. 3. 2. K.I.Bolotin, e.a., Ultrahigh electron mobility in suspended

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graphene. Solid State Communications, 2008. 146: p. 351-355. 3. B.Huard, et al.,Evidence of the role of contacts on the observed electron-hole asymmetry in graphene.Physics Review B, 2008. 78. 4. Meric, I., et al., RF performance of top-gated, zero-bandgap graphene field effect transistors. IEEE International Electron Devices Meeting2008, 2008. 5. I.Meric, et al., Current saturation in zero-bandgap, top-gated graphenefield-effect transistors. Nature Nanotechnology, 2008. 6. Lin, Y.-M., et al., Operation ofGraphene Transistors at Gigahertz Frequencies. Nano Letters, Dec 2008. 9(1): p. 422-426. 7. Neto, A.H.C., et al., The electronic properties of graphene. Reviews of ModernPhysics, 2009. 81: p. 109-162. 8. Zhang, Y., et al., Experimental observation of thequantum Hall Effect and Berry’s Phase in graphene. Nature, 2005. 438(10 November):p. 4. 9. Chang, H., et al., Thin Film Field-Effect Phototransistors from Bandgap-Tunable, Solution-Processed, Few-Layer Reduced Graphene Oxide Films. AdvancedMaterials 2010. 10. Wang, X., et al., Room Temperature All-Semiconducting Sub-10-nm Graphene Nanoribbon Field Effect Transistors. Physics Review Letters, 2008. 11.Stampfer, C., et al., Energy gaps in etched graphene nanoribbons. Advanced Materials,2008. 12. Li, X., et al., Chemically Derived, Ultrasmooth Graphene Nanoribbon Semi-conductors. Science, 2008. 13. Denis, P.A., Band gap opening of monolayer and bilayergraphene doped with aluminium, silicon, phosphorus, and sulfur. Chemical PhysicsLetters, 2010. 492: p. 4-6.

Unipolar Graphene Field-Effect TransistorsHong Li, Qing Zhang*, Shouheng Xu


Typical graphene field-effect transistors (GFETs) show ambipolar conduction that isunfavorable for many electronic applications. In this work, we report on the developmentof unipolar GFETs. We find that titanium oxide situated on graphene surface inducessignificant hole doping that is confirmed by Raman characterization. The thresholdvoltages of the unipolar p-type GFETs are determined by the density of the titaniumoxide decoration that is controllable through an etching process. XPS results show thattitanium oxide, instead of titanium, plays the role of hole donor. An annealing processfollowed by coating a silicon nitride passivation layer can convert the p-type GFETs tounipolar n-type GFETs. The significant threshold voltage variation from p to n-typeGFETs suggests that doping modulation is the dominant mechanism for the conductiontype conversion.

A Conductance-preserving Approach of Covalent Functionalization on Single WallCarbon NanotubesChao Liu, Qing Zhang*, Nicola Marzari, Francesco Stellacci, Lianxi Zheng, ZhaoyaoZhan, Zhiqiang Luo

Friday 2 PM, Concourse, Both No. 2, Panel B1

We report on the unique structural and electrical properties of dichlorocarbene func-

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tionalized single walled carbon nanotubes (SWCNTs). Dichlorocarbene and hydrogenatoms are covalently attached to an individual metallic SWCNT successively. Whilehydrogen atoms significantly degrade the conductivity of the SWCNT, dichlorocarbenedoes not result in any detectable variation in the conductivity. The influence of dichloro-carbene on the conductance of the SWCNT is in sharp contrast with hydrogenation andother reported covalent functionalizations such as fluorination, osmylation, ozonolysis,etc. The conductance-preserving behavior of the SWCNT modified by dichlorocarbenecan serve as a solid experimental evidence for a theoretical prediction in which the co-valent attachment of dichlorocarbene breaks sidewall C-C bond of the SWCNT, leadingto retention of two sp2 carbon bonding characteristics rather than formation of two sp3rehybridization bonds.

Carbon Nanotube Network Transistors for Complementary Logic Gate ArraysPingqi Gao, Qing Zhang*


Single-walled carbon nanotube (SWNT) network possesses inherited unique electricalcharacteristic of individual SWNTs. SWNT network field effect transistors (NET-FETs)are readily suitable for a scalable integration if an efficient technique of fabricatinghigh performance n- and p- type SWNT -NET-FETs at a large scale and low cost isdeveloped. In this presentation, we report that depositing Si3N4 and Al2O3 dielectriclayers on the as-fabricated SWNT-NET-FETs can yield both air-stable n- and p-typeFETs, respectively. The n-type FETs are formed with two possible reasons: (1) oxygenabsorbed on the sidewalls of the SWNTs and/or SWNTs-metal contacts was eliminatedduring the Si3N4 deposition process. Oxygen on the sidewalls may promote electronstransfer from the SWNTs to aqueous oxygen redox couples. While, oxygen adsorbed atthe interface between the SWNTs and metal contacts could increase the work functionof the metal that can increase the Schottky barrier (SB) for electrons transport. (2) Theinduced positive fixed interface charge between the nitride and SiO2 surface could changethe potential profile in the devices, bend the SB at the contact pads and facilitate electroninjecting. Oppositely, Al2O3 thin film deposited by e-beam evaporation processes a quiteloose structure, which allows oxygen to access to the SWNT network and metal contacts,thus the p-type behavior is preserved. The two types of SWNT-NET-FETs have nearlyidentical properties, i.e., mobilities as high as 80 cm2V-1s-1, subthreshold slopes as lowas 130 mVdec-1, operating gate voltages less than 4 V, on/off ratios larger than 104 andseveral kilohertz switching speeds. Complementary inverters, NOR, NAND, OR, ANDlogic gates have been achieved from integrating these p- and n-type SWNT-NET-FETs.

Fabrication of p- and n-type field effect transistors from solution processable

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semiconducting single-walled carbon nanotubesRaj Kumar, Zhang Qing*, Ashok Kumar, Mary B Chan Park


An easy and effective controllable chemical method is reported here for the fabricationof p- as well as n-type single walled carbon nanotube (SWCNT) based field effect transis-tors (FETs). Separated semiconducting SWCNTs without any intentional doping usedas the channels of p-type SWCNT-FETs. While for n-type SWCNT-FETs, doping ofSWCNTs is carried out in SWCNT suspension with piperidine. The Fermi level upshiftdue to electron transfer from the amine group in piperidine to the SWCNT is suggestedto the origin of as prepared n-type behavior of device in open air. We demonstrate thefeasibility of this approach for logic circuits by fabricating a simple inverter using theback-gate geometry

Preparation of TiO2 nanoparticles by molten salt method and its Li-cycling studiesValerie Teoh Xiao Wei Wei, Nguyen Thi Bao Nguyen Nguyen, Michelle Lim Yi YingYing, M V Reddy*, B Vr Chowdari


Preparation of TiO2 nanoparticles by molten salt method and its Li-cycling studiesValerie Teoh Xiao Wei 1,2, Nguyen Thi Bao Nguyen 1,2, Michelle Lim Yi Ying 1,2, M.V.Reddy 2*, B. V.R. Chowdari 2* 1 NUS High School of Math and Science, 20 ClementiAvenue 1, Singapore 129957 2 Solid State Ionics / Advanced Batteries Lab, PhysicsDepartment, National University of Singapore, Singapore 117542

TiO2 nanoparticles are used in various applications such as pigments, sensors, photocatalysts, solar cells and electrode material. Literature studies show that depending onpreparation conditions, for example such as method of preparation and temperature,electrochemical properties will be influenced. This project focuses on making use ofthis simple, low cost method to prepare single phase TiO2 nanoparticles for its usein lithium batteries. We adopted simple molten salt method (MSM) to prepare TiO2nanoparticles, using 0.88M LiNO3:0.12M LiCl molten salt at 280°C for 2 hours. X-ray diffraction studies on the MSM TiO2 nanoparticles showed a single anatase phasewith tetragonal structure and lattice parameter values of a = 4.79 A and c= 9.50 A.Transmission electron microscopy (TEM) images of MSM TiO2 nanoparticles shows 5to 20 nm sized particles. The BET surface areas of prepared MSM TiO2 nanoparticlesare 200 m2/g. Upon further reheating at 500°C, 650oC, 750oC and 800oC, the surfacearea decreases from 80 to 0.7 m2/g. Prepared powders densities about 3.7 g/cm3, whichcompares well with the theoretical density calculated from the XRD method. Cyclicvoltammetry studies on TiO2 nanoparticles show main cathodic and anodic redox peaksat 1.75 and 1.9 V respectively. Galavanostatic cycling studies were done on bothMSM TiO2 nanoparticles and commercial material at a current rate of 33 mA/g, up to60 cycles. MSM TiO2 nanoparticles deliver a high capacity of 180 mAh/g at the end ofthe 50th cycle, corresponding to 0.54 mole of Li, whereas commercial TiO2 nanoparticles

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deliver a capacity of 50 mAh/g. Studies carried out on the various reheated MSM TiO2nanoparticles show that capacity decreases with an increase in temperature and thatthe rutile phase nanoparticles (heated at 800oC) showed the lowest reversible capacity.Our high surface area MSM TiO2 nanoparticles (200 m2/g) can be used as an promisingmaterial in the area of solar cells, water purification and health care.

Preparation of Li1.06Mn1.94O4 and Li1.03Mn1.97O4 by polymer precursor methodand its electrochemical performance for lithium-ion batteriesPoh Yu Quan, Shahid Hussain Nowshad Nowshad, Hsu En-Chi Emmanuel Emmanuel,M V Reddy*, B V R Chowdari

Friday 2 PM, Concourse, Both No. 3, Panel C1

LiMn2O4 is an alternative cheap and eco-friendly cathode material to replace theLiCoO2 for use in the high-power lithium ion batteries. It undergoes capacity fading dueto the instability of the Li-free [Mn2O4] frame work, and also to the dissolution of Mn intothe electrolyte which attributes to the Jahn-Teller effect on Mn3+. Excess of Li-dopingon LiMn2O4 is to improve the cycling stability and reduce or suppress capacity fading.We prepared Li1.03Mn1.97O4 and Li1.06Mn1.94O4 by polymer precursor method at650°C for 8 hour in air. X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM)and Brunauer-Emmett-Teller (BET) surface area and density techniques were used tocharacterise the compounds. Cyclic voltammetry studies were carried out in the potentialrange of 3.5-4.4V at scan rate of 0.058 mV/sec. Li-doped LiMn2O4 showed the maincathodic and anodic redox peaks at 3.9/4.0 and 4.1/4.15V respectively. The reversiblecharge capacities of Li1.06Mn1.94O4 at a current rate of 30mA/g at end of the 2ndand 99th cycle are of 99 and 95 (±3) mAh/g respectively; and at a current rate of 60mA/g at end of 2nd and 99th cycle are 67 and 65 (±3) mAh/g; whereas Li1.03Mn1.97O4shows a stable cycling capacity of 88 mAh/g at a current rate of 30 mA/g at the end of40th cycle and high current of 360 mA/g showed a reversible capacity of 85 mAh/g atthe end of 200 cycles. We will discuss long term cycling studies and observed reactionmechanisms in detail.

Studies on high voltage (4.8V) cathode, Li[Ni0.5Mn1.5 ]O4 for lithium-ion batteriesHerng Yi Cheng, Tham Jun Han Han, Yuan Chen Yang, Goh Hock Leong, M V Reddy*,B V R Chowdari


In our project have prepared high voltage cathode (4.8V), Li[Ni0.5Mn1.5]O4 by usingthe Polyvinylpyrrolidone (PVP) as precursor at a temperatures ranges from 700-750°C,for 6h in air. The Rietveld refined X-ray diffraction patterns of Li[Ni0.5Mn1.5] O4 showeda spinel type structure with a lattice parameter value of a 8.174(2)A. The ScanningElectron Microscope (SEM) images show submicron sized particles in the range, 200-300 nm. Prepared powders was characterized by density and BET surface area methods.Cathodic electrochemical properties were evaluated using Cyclic Voltammetry (CV) and

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Galvanostatic Cycling in the range 3.5–5.0 V vs. Li metal, at ambient temperature. CVstudies show a minor peak at 4.0 V due to the Mn3+/4+ redox couple, and mainanodic/cathodic peaks at 4.75/4.6 V and 4.8/4.7 V corresponding to the Ni2+/3+/4+redox couple. The galvanostatic Cycling studies were carried out at a current rate of 30mA/g and 120 mA/g, at room temperature. The reversible capacities are in the range,110- 128 (± 3) at the end of 15th cycle. The electrochemical studies were compared withother methods and rate capability were discussed. The charge-transfer and Li-transport,diffusion studies was carried using Impedance spectroscopy technique in the frequencyrange, 0.18MHz to 3 mHZ, at 10 mV ac amplitude.

Narrowband PPKTP Source for Entangled Polarization PhotonsSiddarth Koduru Joshi*, Felix Anger, Christian Kurtsiefer


We present our efforts to create a narrow-bandwidth source of entangled photonswith a high spectral brightness to facilitate their interaction with single trapped atoms.A pump beam wavelength =405 nm, focused into a type II PPKTP crystal, is down-converted to obtain signal and idler beams; their frequency can be tuned via the tem-perature of the crystal. By changing the beam waist inside the crystal, we determinethe optimal focusing parameters for our source. We observe that weak focusing resultsin large pair to single ratio (efficiency). For a beam waist of .170 mm (for both thepump and target modes) we observe efficiencies ¿ 25We use a narrow-band (160 MHz)pump beam and find a narrow bandwidth (82 GHz) of the down-converted beams com-patible with what is expected due to the finite length of the crystal (55 GHz). Toproduce polarization entangled pairs of photons, we pump the crystal from both direc-tions inside a Sagnac interferometer. This geometry allows to decouple the pump andthe downconverted beams. Furthermore, experimental measurements of the tempera-ture dependence of the wavelengths of the signal and the idler beams have been found tomatch theoretical calculations. The decoupled geometry for pump and downconvertedlight allows for a decoupling of alignment degrees of freedom and also for an independentoptimization of optical components like the PBS, resulting in a potential for very cleanpolarization entanglement. We note that, counterintuitively to the implemented Sagnacgeometry, this design, requires interferometric stability since the auto-compensation ofthe path length differences between pump and down converted modes, a feature of theSagnac geometry, is lost. References 1 Marco Fiorentino, Gaetan Messin, ChristopherE. Kuklewicz, Franco N. C. Wong, and Jeffrey H. Shapiro , “Generation of ultrabrighttunable polarization entanglement without spatial, spectral, or temporal constraints”,Phys. Rev. A 69, 041801(R) (2004). 2 F. Konig, EJ Mason, FNC Wong, and MA Al-bota, “Efficient and spectrally bright source of polarization entangled photons” , Phys.Rev. A 71, 033805 (2005). 3 Ryan S. Bennink, “Optimal collinear Gaussian beams forspontaneous parametric down-conversion ”, Phys. Rev. A 81, 053805 (2010).

X-Ray diffraction and X-Ray absorption spectroscopy studies on Lithium battery

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materialsM V Reddy*, B V R Chowdari


X-Ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) techniques wereused to examine the lattice parameters, oxidation state, electronic and local structureof the lithium battery electrode materials. I will present our group research results onXRD and XAS studies on bare and Ru, Co, Cr, Al doped LiMn2O4, layered Ni, Mndoped LiCoO2, CoN and V-edge, LiVPO4F, V2O5 and LiV3O8 and metal cluster com-pounds ex: Mn2Mo3O8, LiYMo3O8. The above compounds were prepared by usingthe following methods: molten salt method, Polymer precursor method, Carbothermalreduction method, co-precipitation method, fallowed by solid state reaction and am-monolysis method. Materials were well characterized by wide variety of physical andelectroanalytical techniques.

Optimizing Pair Collection Efficiency in Spontaneous Parametric Down-ConversionHou Shun Poh*, Tien Tjuen Ng*, Kelvin Lin*, Christian Kurtsiefer*

Friday 2 PM, Concourse, Both No. 4, Panel D1

Bell inequalities serve to test the Einstein-Podolsky-Rosen (EPR) hypothesis of localrealism in quantum mechanics. Violations of these inequalities have been demonstratedin many experiments involving photonic quantum systems. However, these tests remainsubject of debate because of the low quantum efficiency of the current Silicon detectors(quantum efficiency 50-60

We try to optimize the pair collection efficiency, which is quantified by the pair/singleratio, by adopting a collinear configuration with a type-II BBO crystal. Separation of thetwo target modes with orthogonal polarizations is done with a polarizing beam splitter(PBS). The main challenges here are to maximize the mode overlap and minimize lossesin the optical elements in the setup.

The measured collection efficiency η is given by: η = ηT.(η1η2)(1/2).Rc/(R1R2),where Rc, R1, and R2 are the actual pair and single rates from down-conversion. Thevariable ηT is the combined optical transmissions after the crystal, and η1 and η2 arethe detector efficiencies (around 50

Ultracold Atoms and Cavity Quantum ElectrodynamicsKyle Arnold*, Markus Baden, Murray Barrett


We report our progress towards an atom-photon node using cavity QED. Our systemutilizes a far detuned optical lattice to transport cold atoms into a high finesse cavity,anywhere from a single atom to several thousand. We will present our ongoing investi-gations with this system. In particular we have studied effect of varying coupling on thecavity spectrum with multiple hyperfine levels.

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Classical dynamics of interacting qubits driven by a quantum fieldB. M. Rodriguez-Lara*, R.-K. Lee


We present a stability analysis of a qubit ensemble driven by a quantum field inthe semi-classical limit. Transitions from Rabi to Josephson dynamics are identifieddepending on both the intra-qubit interactions to field-ensemble coupling ratio and theratio between the total excitation number and the ensemble size. The quantized field isfound to produce asymmetric dynamics for symmetric initial conditions for both Rabiand Josephson oscillations.

Exact Solution of the Fokker-Planck Equation with arbitrary AC DrivingChee Kong Lee*, Jiangbin Gong


We use the matrix continued fraction to solve the Fokker Planck equation with ar-bitrary AC driving. We first convert the Fokker Planck equation into a set of linearalgebraic equations by expansion of complete sets. With appropriate choice of basisfunction, we obtain short-ranged index coupling such that continued fraction can beimplemented. Two non-linear systems of different nature are studied: molecular dipole(rotational Brownian motion) and particle in a periodic potential (translational Brown-ian motion). The full dynamics is concisely presented in the hysteresis loops. As drivingfield increases, we observe pronounced non-linear effect, manifested in the deformationof the hysteresis loops.

Finite-key security against coherent attacks in quantum key distributionLana Sheridan, Thinh Phuc Le*, Valerio Scarani

Friday 2 PM, Concourse, Both No. 5, Panel E1

Christandl et al (2009 Phys. Rev. Lett. 102 020504) provide, in particular, thepossibility of studying unconditional security in the finite-key regime for all discrete-variable protocols. We spell out this bound from their general formalism. Then, weapply it in the analysis of a recently proposed protocol (Laing et al 2010 Phys. Rev.A 82 012304). This protocol is meaningful when the alignment of Alice’s and Bob’sreference frames is not monitored and may vary with time. In this scenario, the notionof asymptotic key rate has hardly any operational meaning, because if one waits toolong a time, the average correlations are smeared out and no security can be inferred.Therefore, finite-key analysis is necessary for finding the maximal achievable secret keyrate and the corresponding optimal number of signals.

31

Lenses as an Atom-Photon Interface: A Simple ModelColin Teo*, Valerio Scarani


Strong interaction between the light field and an atom is often achieved with cavi-ties. Recent experiments have used a different configuration: a propagating light fieldis strongly focused using a system of lenses, the atom being supposed to sit at the focalposition. In reality, this last condition holds only up to some approximation; in partic-ular, at any finite temperature, the atom position fluctuates. We present a formalismthat describes the focalized field and the atom sitting at an arbitrary position. As afirst application, we show that thermal fluctuations do account for the extinction datareported in [1].

References: [1] M. K. Tey et al., Nature Physics 4, 924 (2008) [2] M. K. Tey et al.,New Jour. Phys. 11, 043011 (2009)

A quantum Turing machineJanus H. Wesenberg*


We study a recently proposed quantum information processing platform based on anelectron spin ensemble coupled to a coplanar waveguide resonator1. We are particularlyinterested in the shear effect that is observed when a magnetic field gradient is appliedto the spin ensemble while it is interacting strongly with the cavity. The shear effectshould be observable in a number of physical systems where an inhomogeneously broad-ened ensemble of independent subsystems interact with a central system, and where theinhomogeneous broadening can be effectively inverted by e.g. spin echo techniques.

Investigation on the Mechanism of Aggregation of Amyloid Peptides Revealed byMolecular Dynamic StudyLina Zhao*, Lock Yue Chew

Saturday 9.40 AM, Concourse, Both No. 5, Panel E4

Alzheimer’s disease (AD) is a progressive, irreversible and neurodegerative disorderthat slowly destroys memory and thinking skills. The early symptoms of AD includeloss of short-term memory, difficulty solving problems or with familiar tasks, decline inspacial reasoning, language difficulties, withdrawal from social functions, mood swingsand personality changes, et. al.

Molecular dynamics is deterministic, which means that the future state of the systemis completely determined by its present state. The central idea is to solve Newton’sequations of motion for a system of atoms which interact via a potential energy func-tion known as a force field. Force field considers the atomic composition of a moleculeto be a collection of masses interacting with each other via forces described by empir-ical energy functions. Many force fields can be interpreted in terms of the intra- and

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inter-molecular forces within the system. The intra-molecular forces include the bond-stretching forces, angle bending and torsion potential, and the non-bond interactionsinclude the electrostatic and Van Der Waals interactions.

Search for Elemental Topological Insulators from Bismuth and AntimonyXuesen Wang*

Saturday 9.40 AM, Concourse, Both No. 6, Panel F1

Topological insulators (TIs) are insulators in the bulk but exhibit spin-polarizedtopological-protected gap-less spin-polarized boundary states. TIs are predicted use-ful in spintronics and quantum computing. Currently, the theoretically predicted andexperimentally identified TIs are either compounds or alloys. The intrinsic defects anddisorders in these materials degrade their electronic properties far from the ideal ones.We explored two pure elemental TIs, namely bismuth (111) bilayer (BL) and antimonyultrathin films. 1-BL Bi(111) has been predicated a 2-dimensional (2D) TI, but yet tobe realized experimentally. We found proper procedure to grow 1-BL Bi(111) and thencharacterized it with scanning tunneling microscopy/spectroscopy (STM/STS). Edgestates have been observed which also exhibit other TI characteristics. Bulk Sb is asemimetal but possesses topological-protected surface states. Taking advantage of quan-tum confinement effect, a quasi-3D TI can be realized with Sb nanostructures. Ourcomputational studies indicate that Sb(111) thin films in the thickness range 1.9-6 nmare gapped in bulk but with a single Dirac-cone surface states. These surface states havebeen identified in our STM/STS mapping. These elemental TIs should offer certain ad-vantages over compounds or alloys that are essential to applications, such as low bulkand surface defect densities.

Dual Species Atom InterferometerAndrew Chew*, Cheng Tang, Maral Sahelgozin, Chao Bo Zhang*, Rainer Dumke*


Atomic interferometers have many practical uses both in the fields of navigation andprecision measurement. Atom Interferometers have been used to measure the fine struc-ture constant, the local gravitational acceleration, and make inertial measurements allwith high levels of accuracy. Current efforts in this field are working towards the goalof portability. However, one disadvantage of a single species Atomic Interferometer isthat the rate of measurement is low. Here, we present the progress towards a dualspecies Atom Interferometer with two atomic species, namely Rb87 and Ce133 withtrapping and cooling frequencies far detuned from each other.The advantages of sucha dual species Atom Interferometer include allowing for quasi-continuous measurement,and simultaneous multi-axis measurements. The experimental setup is designed withthe goal of portability and stability.

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Black holes on gravitational instantonsYu Chen*, Edward Teo


We classify and construct five-dimensional black holes, with R×U(1)2 isometry, ongravitational instantons. These black holes have spatial backgrounds which are grav-itational instantons with U(1)×U(1) isometry, and are completely regular space-timesoutside the event horizon. Most of the known exact five-dimensional black hole solutionscan be classified within this scheme. Amongst the new solutions that are presented arestatic black holes on the Euclidean Kerr and Taub-bolt instantons. We also present arotating black hole on the Eguchi-Hanson instanton.

A coordinated molecular ‘fishing’ mechanism in Kar3/Vik1 heterodimeric kinesinHou Ruizheng, Wang Zhisong*


Kar3 is a kinesin motor that facilitates chromosome segregation during cell division.Unlike many members of the kinesin superfamily, Kar3 forms a heterodimer with non-motor protein Vik1 or Cik1 in vivo. The heterodimers show ATP-driven minus-end di-rected motility along a microtubule (MT) lattice, and also serve as depolymerase at theMT ends. The molecular mechanisms behind this dual functionality remain mysterious.Here, a molecular mechanical model for the Kar3/Vik1 heterodimer based on structural,kinetic and motility data reveals a long-range chemomechanical transmission mechanismthat resembles a familiar fishing tactic. By this molecular ‘fishing’, ATP-binding to Kar3dissociates catalytically inactive Vik1 off MT to facilitate minus-end sliding of the dimeron the MT lattice. When the dimer binds the frayed ends of MT, the fishing channelsATP hydrolysis energy into MT deploymerization by a mechanochemical effect. Themolecular fishing thus provides a unified mechanistic ground for Kar3’s dual functional-ity. The fishing-promoted depolymerization differs from the depolymerase mechanismsfound in homodimeric kinesins. The fishing also enables intermolecular coordinationwith a chemomechanical coupling feature different from the paradigmatic pattern of ho-modimeric motors. This study rationalizes some puzzling experimental observation, andsuggests new experiments for further elucidation of the fishing mechanism.

Band gap engineering in grapheneAihua Zhang*, Chun Zhang*

Saturday 9.40 AM, Concourse, Both No. 7, Panel G1

The fact that pristine graphene is gapless has hindered its application as the electronicmaterial. In this talk, I will give a presentation on our recent theoretical work onthe band gap engineering of graphene. Our work focuses on three different methods:graphene superlattice, graphene antidot, and graphene nanoribbon edge structure. Thegraphene superlattice is formed when a periodic external potential is applied to graphene.

34

A band gap will open in the graphene superlattice due to either the breaking of ABsublattice symmetry or the inter-valley scattering. The overall band gap opening thenwill be determined by the interaction between these two effects. The graphene antidotlattice is a periodic array of holes in graphene. Our calculation reveals that band gapopening will occur only for certain periodicity if the holes align in the zigzag direction,which can be related to the inter-valley scattering. The scaling law of band gap withrespect to the antidote lattice size is shown to be exponential. The zigzag graphenenanoribbon is well known to be metallic due to degenerated edge states at the Fermilevel, if spin-polarization is not considered. We demonstrate that these edge states can beremoved, thus resulting a semiconducting nanoribbon, when an edge structure satisfyinga certain condition is present. Through ab initio transport calculation, we show thatthis semiconducting nanoribbon can be used to fabricate a field effect transistor with ahigh on-off ratio.

A photonic Luttinger liquid and spin-charge separation in a quantum optical systemDimitris Angelakis, Mingxia Huo, Elica Kyoseva*, Leong Chuan Kwek*


In this work we show that light-matter excitations (polaritons) generated inside ahollow one-dimensional fiber filled with two types of atoms, can exhibit Luttinger liquidbehaviour. We explain how to prepare and drive this quantum-optical system to astrongly interacting regime, described by a bosonic two component Lieb Lininger model.Utilizing the connection between strongly interacting bosonic and fermionic systems,we show how spin-charge separation could be observed by probing the correlations inthe polaritons. This is performed by rst mapping the polaritons to propagating photonpulses and then measuring the eective photonic spin and charge densities and velocitiesby analyzing the correlations in the emitted photon spectrum. The necessary regime ofinteractions is achievable with current quantum optical technology.

Enhanced Field Emission Properties of α-Fe2O3 Nanostructures with the Removalof Absorbed Gas MoleculesJunpeng Lu, Tao Yun, Minrui Zheng, Chorng Haur Sow*


Quasi-one-dimensional α-Fe2O3 nanostructure arrays of four different morphologies(random nanoflakes, random nanobelts, quasi-aligned nanostrips and quasi-aligned nanonee-dles) were successfully synthesized via a simple heating process. Field emission measure-ments indicate that the α-Fe2O3 nanoneedle arrays are superior field emitter exhibitinglow turn-on voltage, high current density and large field-enhancement factor due to bet-ter vertical alignment and higher aspect ratio. In addition, we found that absorbedoxygen molecules greatly hindered the field emission performance of the nanostructures.Prolonged field emission process could drive the oxygen molecules away and gave riseto markedly improved and efficient α-Fe2O3 nanostructures field emitter. The improved

35

field emission is attributed to desorption of the oxygen molecules during the field emis-sion process.

Simulating mesoscopic spin-boson models with a quantum optical systemElica Kyoseva*, Leong Chuan Kwek, Dimitris G. Angelakis


Mesoscopic condensed matter physics has found a broad application in atomic physicsand quantum computing. A celebrated problem from mesoscopic physics with relevancein quantum optics is the spin-boson model which studies the interaction of a two-statesystem with a bath of harmonic oscillators. Coupled cavity arrays represent a verypromising hybrid light-matter quantum optical system which has found many appli-cations in quantum physics. These range from quantum information processing andmeasurement-based quantum computing to quantum simulations of condensed matterproblems and others. This is due to the rich physics exhibited by the CCAs based onthe interplay between light and matter. Here, we show that a linear array of coupledcavities can be used for the natural realisation of the spin-boson model while providinga wide range of easily tunable parameters.

Self-organized Mesocrystal built up of Nanowires: Octahedral Cu2O SupercrystalsSuzi Deng*, Haiming Fan, Chornghaur Sow

Saturday 9.40 AM, Concourse, Both No. 8, Panel H1

Here we report a Cu2O mesocrystal, in which anisotropic nanowires are assembledin an interpenetrating manner, with high vectorial order and control over the inter-dendritic space, into a single crystal like-octahedron possessing well-defined externalfacets. From time-dependent SEM images, a multistep organizing principle involvingdissolution-recrystallization, dendritic expansion, self-organization of smaller buildingblocks via oriented aggregation and edge sharing growth is proposed. In addition, thebranching pattern and type of mesocrystal is tunable by the choice of organic additiveand pH. We highlight a few peculiar aspects of the mesocrystals formed by our route: (1)the mesocrystals are composed of high aspect ratio nano- building block like nanowires;(2) the mesocrystals have a low filling factor, and (3) the observation of sierpinski-likevoided octahedral mesocrystal intermediates.

Neutron yield performance of newly developed NX-3 dense plasma focus deviceRishi Verma, T. L. Tan, Paul Lee, A. Talebitaher, H. Shariff, S. V. Springham, A.Shyam, R. S. Rawat*


The results of experiments carried out on a newly developed dense plasma focus device(NX-3) that has recently been made operational at Plasma Radiation Source Lab, NIE,Nanyang Technological University, Singapore is reported. The 20kJ pulsed power system

36

of NX-3 plasma focus device comprises of eight modules (of 2.5kJ each) and cumulativelydelivers peak current in the range of 200kA to 600kA (depending upon load and operatingparameters) in a quarter time period of less than 3.5 microseconds. The major objectiveof preliminary phase of experiments was to investigate the neutron yield performance ofthis device at various deuterium filling gas pressures. At 10kJ operation, the averageneutron yield has been found to be in the order of 109 neutrons/pulse for the deuteriumfilling gas pressure range of 6 to 8mbar. Both the time integrated and time resolvedtechniques are employed to study the neutron emissions from this novel device. Thediagnostics used during these experiments were: He and Be detector for the neutronyield measurements, NE102A and CsI scintillator-photomultiplier detectors for gatheringthe time resolved information of hard X-ray and neutron emission and Rogowski coilfor di/dt, current measurements. The main application objective of this high neutronyield dense plasma focus device development is: (i) to explore the feasibility studytowards development Pulsed Fast Neutron Analysis (PFNA) system for explosive andcontraband material detection and (ii) to conduct novel fusion reactor material studies,by investigating their suitability as plasma facing component materials in large upcomingfusion facilities.

Wireless Energy Transfer to Piezoelectric Devices through Magnetic ResonanceTung Nguyen*, Zi Kai Hang*


We research on the feasibility of using the concept of magnetic inductance to powerpiezoelectric material wirelessly. Two conducting coils, one connected to the voltagesource and one connected to the testing piezoelectric device were set up, with the piezo-electric device put inside a water container simulating the water medium in its everydayapplication. At resonance frequency and secondary resonance frequency, with other vari-ables kept at standard level, the piezoelectric device worked well, proving that wirelesspower transfer is feasible. The effect of secondary resonance frequency were tested indifferent combinations of coils and the results were analogous to the effect of dielectrichysteresis. Controllable variables were also tested to identify the optimum parametersthat should be used in order to achieve maximum efficiency. Resonating coils of varyingsize and shape were built and experimented with to find the most efficient structure thatcan be used to transfer energy wirelessly to the piezoelectric device.

Our result show the potential enhancement for applications of piezoelectric materialsthat are used in ultrasonic cleaning, implantable heart pacer, implantable drug deliverydevices as they can now operate without a battery that must be replaced periodicallyand they can now be easily controlled using an external wireless power source.

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On the quantum phase transition in XX modelWonmin Son*, Vlatko Vedral


In this presentation, the state structure of spectrums of the XX model has beendiscussed on the view of quantum phase transition and entanglement. Especially, thecritical behaviors of the model in the ground state and the thermally excited state havebeen identified through the couple of different properties. With the complete solutionsof the model - not just energy spectrum but also the exact energy eigenstate -, it waspossible to identified several interesting physical behavior of the states, continuous phasetransition at the ground state, quasi long range behavior of entanglement in two spinsof the chain, and singular behavior of purity (or mixedness) which is related to quantumphase transition. The discussion is made in various limits, at zero temperature as wellas at a thermal equilibrium, in the finite chain limit and in the thermodynamic limit.

Construction of a Liquid Mirror Telescope and Investigating the Effects of MediumProperties on Image QualityXue Wei Chan*, Jia Xun Chua*, Jonathan Xuan Jie Khoo*

Saturday 9.40 AM, Concourse, Both No. 9, Panel I1

This project involves constructing a portable liquid mirror telescope, which has theadvantages of being cheap, lightweight and portable compared to conventional telescopes.The prototype consists of a basin to contain the liquid, rotated by a motor to form aparabolic reflective surface. A charge-coupled device (CCD) positioned at the focal pointcaptures the focused light rays to generate an image.

The constructed set-up was subsequently characterized, which involved finding thefocal point at different voltages to accurately position the charge-coupled device, esti-mating the curvature of the liquid surface to ascertain it is parabolic and identifying theabsorbance values of various colored liquids to determine the appropriate colored liquidto be used.

Our set-up can function with various applied voltages and hence the rotational velocityand focal point of our telescope can be conveniently varied. It is also compatible withportable power sources and lightweight, weighing only 2 kg, hence being convenient forastronomers to bring outfield.

Attempts were made to capture images of bright objects like Sirius and the Moonwhile they were close to the zenith. However, because of the limited light-gatheringpower of our prototype and the presence of significant light pollution in Singapore, theimages captured were not of high resolution. The relationship between liquid color andimage quality was also investigated by obtaining images of a green laser beam and theMoon as well, but there were no conclusive differences observed in the images capturedusing differently-colored liquids.

38

Cavity Quantum Electrodynamics with Trapped IonsNick Lewty*, Boon Leng Chuah, Murray Barrett


We report on our current progress into combining a trapped ion with a high finesseoptical resonator, which is useful in certain quantum information processing schemes.There are currently two directions being persuaded to achieve strong coupling betweenthe ion and the cavity field. The first is to combine cavity mirrors with a RoC (radius ofcurvature) = 2.5cm with a linear paul trap. The second is to use micro cavity mirrors thatare currently been developed within our group, that have a Roc = 3mm, in combinationwith a surface trap. The second method provides greater coupling strengths, at theexpenses of being more difficult to combine with an ion trap. The measured finesse ofthe RoC = 2.5cm is 60,000 and the RoC = 3mm is greater than 15,000, with these finessevalues the ion cavity system will be in the strong coupling regime.

CONSTRUCTING A LIQUID MIRROR TELESCOPE AND INVESTIGATING THEEFFECTS OF ROTATIONAL SPEED AND VISCOSITY OF SURFACE LIQUIDShuin Jian Wu*, Yong Hui Toh*, Chun Mei Tay*


We are investigating Liquid Mirror Telescope (LMT) design, construction and op-eration, and focusing on the correlation between variables like rotational velocity andmedium viscosity with the focal length of the system. The results obtained were inagreement with our preliminary hypotheses. It was observed that focal length had aninverse relationship with both rotational velocity and liquid viscosity. Moreover, all threesurface liquids were rather smooth parabolic surfaces, as the R2 values for all surfaceliquids were more than 0.98, and the χ2/doF values were relatively small. However, theoil surfaces were smoother parabolas compared to water surface, as the P-values associ-ated with the χ2/doF value for both water plots were ¡ 0.01, whereas those for the oilplots were ¿ 0.70.

Images of the Moon were taken using the water-based LMT, and the quality of imagesobtained when oil surfaces were used was better than without.

Entropy and enthalpy change during DNA overstretching transitionZhang Xinghua, Patrick Doyle, Jie Yan*


In physiological buffer conditions, a tension induced structural transition of DNAoccurs in a narrow range of force around 65 pN, after which the double helix becomesabout 1.7 times the B-DNA contour length . After 15-years of debate of the nature of thistransition, it has been shown recently that, in addition to a force-induced “unpeeling” ofone strand from the other, a previously hypothesized “B-to-S” transition from B-DNAto a mysterious elongated double stranded “S-DNA” exists . Unlike the well-studied

39

strand-unpeeling transition, the physics of the “B-to-S” transition and the resulting S-DNA has remained unknown. Here, we report that the “B-to-S” transition involves anentropy change of S 3.6 cal/(K.mol) and an enthalpy change of H 1.1 kcal/mol, bothbeing significantly smaller than the energy data measured in the thermally induced DNAmelting transition . We also report that the distance between the two strands in theS-DNA must be within the Debye screening length. Taken together, our results showthat the “B-to-S” transition leads to an overstretched, highly ordered double-strandedstructure, which cannot be explained any type of melting including both the strand-unpeeling and the parallel-melting mechanisms .

An Investigation Into Solar Activity And Its Effects On TelecommunicationsOng Seng Peing*, Lim Tiong Wei Benny*, Cai Shu Ting*

Saturday 9.40 AM, Concourse, Both No. 10, Panel J1

We present an analysis of solar activities and their effects on the local telephonenetwork. To that effect, we have assembled a radio dipole antenna system in accordanceto technical schematics from the NASA RadioJOVE project. This system has a designedoperating regime centred at 20.1 MHz, which should allow for detection of radio signalsgenerated during solar flares.

We have conducted measurements in Bukit Timah, Singapore; Punggai, Malaysia;and Batam, Indonesia between the 27th May and 22nd December of 2010. These datasets should provide a broad spectrum of environmental variables for our analysis, suchas effects associated with the weather, urban environment and latitudes.

Cross reference is then made with official releases from the SOHO satellite, so as toverify the timings of events we observed with those by NASA scientific group. We alsocarry out comparisons between day-time and night-time measurements, in an attempt toisolate radio signatures as being from the skies. Multiple phasing cables are introduced,and when coupled with proper orientation of the antenna array, allows us to effectively’point’ the set-up, and thus increase our confidence in identifying the source of anyparticular signal.

Investigation of the Gauss Sum Factorisation Algorithm with Quantum DegenerateGasesAnushyam Mohan*, Zhi-Wei Wang*, Chaobo Zhang*, Kin Sung Chan*, Tobias Mueller*,Rainer Dumke*

Saturday 9.40 AM, Concourse, Both No. 10, Panel J2

We propose to implement and test the Gauss sum algorithm for the factorisation oflarge integers using quantum degenerate gases. The experiment will be implemented bycoherently coupling the hyperfine ground states of 87Rb atoms,which serve as a two-level system, by a two-photon Raman transition. We will study the consistency of theexperiment for different trap architectures which would introduce different sources ofdecoherence.

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Author List

Ajay Soni, 20Ariando, 21

Alireza Talebitaher, 20Angelakis, Dimitris, 35Angelakis, Dimitris G., 36Anger, Felix, 29Arnold, Kyle, 30

Baden, Markus, 30Baomin Wang, 17Barrett, Murray, 30, 39Bin Xia, 17Bo Peng, 20Bo Zhang, 5Boon Leng Chuah, 16

Cai Shu Ting, , 40Chan Kin Sung, 17Chan Park, Mary B, 27Chan, Kin Sung, 40Chan, Xue Wei, 38Chen, Yu, 34Cheng, Herng Yi, 28Chew, Andrew, 33Chew, Lock Yue, 32Chorng Haur Sow, 9Chornghaur Sow, 5Chowdari, B V R, 23, 28, 30Chowdari, B Vr, 27Chua, Jia Xun, 38Chuah, Boon Leng, 39Chun Zhang, 9

Da Zhan, 6Deng, Suzi, 36Doyle, Patrick, 39Dumke, Rainer, 33, 40

Elisabeth Rieper, 11Emmanuel, Hsu En-Chi Emmanuel, 28Erik Gauger, 11

Fan, Haiming, 36Fei Wu, 11

Gao, Pingqi, 26Goh, Hock Leong, 23Goh, Yeow Chong, 23Gong, Jiangbin, 31

Haibin Su, 8Han, Tham Jun Han, 28Hang, Zi Kai, 37Hock Siah Lim, 9, 17Hongxia Fu, 13Huihui Pan, 17Huo, Mingxia, 35

Jiabao Yi, 17Jie Yan, 12, 13Jing Ya Sun, 9Jing Yan Haw, 16John Morton, 11Jun Ding, 17Jun Zhang, 20

Kaibin Ruan, 17Khoo, Jonathan Xuan Jie, 38Koduru Joshi, Siddarth, 29Koh, Kenrick, 23Kumar, Ashok, 27Kumar, Raj, 27Kurtsiefer, Christian, 29, 30Kwek, Leong Chuan, 35, 36Kyoseva, Elica, 35, 36

Lan Wang, 17Lana Sheridan, 14Le, Thinh Phuc, 31Lee Paul, 20Lee, Chee Kong, 31Lee, Paul, 36Lee, R.-K., 31Leong, Goh Hock, 28

Lewty, Nick, 39Li, Hong, 24, 25Lim Tiong Wei Benny, , 40Lin, Kelvin, 30Liu, Chao, 25Lu, Junpeng, 35Luo, Zhiqiang, 25

M V Reddy, 19Martial Ducloy, 18Marvin Weinstein, 7Marzari, Nicola, 25Meng Hau Kuok, 9, 17Meng-Chwan Tan, 14Miao Zhou, 9Miguel Navascues, 14Mohan, Anushyam, 40Mueller, Tobias, 40Murray Douglas Barrett, 16

Ng, Tien Tjuen, 30Nguyen Huynh, 15Nguyen, Nguyen Thi Bao Nguyen, 27Nguyen, Tung, 37Nicholas Lewty, 16Nowshad, Shahid Hussain Nowshad, 28

Ong Seng Peing, , 40

Paul Shutler, 20Peng Ren, 17Phil Chan, 6Poh, Hou Shun, 30

Qihua Xiong, 20Qing, Zhang, 27Quan, Poh Yu, 28

Rainer Dumke, 5, 17Rajdeep Singh Rawat, 21Rawat Rajdeep, 20Rawat, R. S., 36Reddy, M V, 27, 28, 30Reddy, M.V., 23Ricksen Winardhi, 12

Rodriguez-Lara, B. M., 31Ruchuan Liu, 11Ruizheng, Hou, 34

Sahelgozin, Maral, 33Scarani, Valerio, 31, 32Ser Choon Ng, 9, 17Shariff, H., 36Sharon Xiaodai Lim, 9Sheridan, Lana, 31Shuyan Xu, 21Shyam, A., 36Simon Benjamin, 11Son, Wonmin, 38Sow, Chorng Haur, 35Sow, Chornghaur, 36Springham, S. V., 36Stellacci, Francesco, 25Stuart Springham, 20Swee Ping Chia, 15

Taiyu, Guo, 23Talebitaher, A., 36Tan, T. L., 36Tang, Cheng, 33Tang, Ying Wei, 23Tay, Chun Mei, 39Teo, Colin, 32Teo, Edward, 34Toh, Yong Hui, 39Tzyh Haur Yang, 14

Valerio Scarani, 14, 16Vanessa Li Zhang, 9, 17Vedral, Vlatko, 38Verma, Rishi, 36Vlatko Vedral, 11

Wang, Xuesen, 33Wang, Zhi-Wei, 40Wei, Valerie Teoh Xiao Wei, 27Weixi Tony, Ding, 23Wesenberg, Janus H., 32Wu, Shuin Jian, 39

42

Xiangyang Liu, 8Xiao Wang, 21Xiaodan Zhao, 8Xiaoguang Li, 17Xinghua, Zhang, 39Xu, Shouheng, 24, 25

Yan, Jie, 39Yang, Yuan Chen, 28Yanyuan Zhao, 20Yin, Zongyou, 24Ying, Michelle Lim Yi Ying, 27Yingying Diao, 11Yong Liu, 17Yu Cai, 14Yuan Ping Feng, 9Yuanyuan Qu, 13Yun, Tao, 35

Ze Xiang Shen, 6Zeping Peng, 20Zhan, Zhaoyao, 25Zhang Bo, 17Zhang, Aihua, 34Zhang, Chao Bo, 33Zhang, Chaobo, 40Zhang, Chun, 34Zhang, Hua, 24Zhang, Qing, 24–26Zhao, Lina, 32Zheng, Lianxi, 25Zheng, Minrui, 35Zhi Kui Wang, 9, 17Zhisong, Wang, 34

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Physics Education Seminar_2011 Annex A

Time Programme Venue

1400

Introduction by Principal NUS High School

1405 Opening address by Guest of Honour – Mdm Low Khah Gek, Director, Curriculum Planning & Development, Ministry of Education

1415 Keynote lecture – Professor Lui Pao Chuen, Advisor, National Research Foundation

1435 Physics In Industry – Mr Aaron Tham, Director (Human Capital Division), Economic Development Board

Auditorium

1450 Break

Concourse

1510 Concurrent sessions

A1 - Physics in Defence/Engineering Dr Teo Kien Boon, Programme Director, DSO National Laboratories (Seminar Room 1)

B1 - Physics in Multidisciplinary Research Professor Andrew Wee Thye Shen, Dean NUS Science Faculty (Seminar Room 2)

C1 – Physics in NUS High School Dr Hang Kim Hoo, Principal NUS High School (Auditorium)

D1 – The future of science learning Dr Markus Grumann, R&D Director, PHYWE GERMANY (Specialized Labs)

A2 – Physics in Industry Mr Winston Tan Managing Director, Corporate Brokers International Pte Ltd, Physics Alumni (Class of 72) (Seminar Room 1)

B2 – Physics Demonstrations A/Prof Sow Chorng Haur, Asst Dean (Outreach), NUS Science Faculty (Seminar Room 2)

C2 – "What works in Lesson Study: The Siglap Secondary Experience" School: Siglap Secondary School (in collaboration with Academy of Singapore Teachers) Presenter: VP of Siglap Sec's, Mrs Yoong Jin Ing and Physics Master Teacher, Dr Charles Chew (Auditorium)

D2 – The future of science learning Dr Markus Grumann, R&D Director, PHYWE GERMANY (Specialized Labs)

Respective

venues

1630 Forum and Q & A - Prof Kwek Leong Chuan (Chair), Prof Andrew Wee, Mr Sin Kim Ho & Dr Hang Kim Hoo Physics in the next 5 years: Challenges and Opportunities

Auditorium

1730 End of Seminar

B. Seminar Room Location

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