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Ultrafast Pulsed Laser Gates for Atomic Qubits
JOINTQUANTUMINSTITUTE
with David Hayes, David Hucul, Le Luo, Andrew Manning,Dzmitry Matsukevich, Peter Maunz, Jonathan Mizrahi,
Steven Olmschenk, Qudsia Quraishi, Crystal Senko, Jon Sterkand Chris Monroe
Wes CampbellU. Maryland and NIST Joint Quantum Institute (USA)
ECTI Durham, UKSeptember 23, 2010
Mode-locked lasers: less scary (?)
PSD
•ps – fs pulse durations•repeatable and clean
]
sech[)(pulseT
ttE
FSR = frep
FSR
Mode-Locked Laser Gates
•Raman transitions: Strong excitation regime
fast single qubit operations
an approach for fast entanglement
•Raman transitions: Weak excitation regime
your favorite cw tasks done with a comb
entanglement of two ions
•Resonant transitions: excite to the P state
photon frequency or polarization qubit
remote entanglement of two ions
171Yb+ spin ½ nucleus
2S1/2
2P1/2
12.6 GHz
hyperfine clock state qubit
370 nm
S. Olmschenk et al., PRA 76, 052314 (2007)
171Yb+ spin ½ nucleus
2S1/2
2P1/2
12.6 GHz
state preparation:optical pumpingS. Olmschenk et al., PRA 76, 052314 (2007)
State detection with 171Yb+
2S1/2
2P1/2
12.6 GHz Number of de tected pho tons
Num
ber
of
exp
erim
ents
in th
ousa
nds
0
2
4
6
8
10
12
14
16
0 5 10 15 20
simple discriminatordetection fidelity 98.5%
Number of de tected pho tons
Num
ber
of
exp
erim
ents
in th
ousa
nds
0
2
4
6
8
10
12
14
16
0 5 10 15 20Number of de tected pho tons
Num
ber
of
exp
erim
ents
in th
ousa
nds
0
2
4
6
8
10
12
14
16
0 5 10 15 20
S. Olmschenk et al., PRA 76, 052314 (2007)
• Ions for QI preparation, storage, and readout• Photons for QI transmission, communication
ion-photon entanglement
•Bandwidth must exceed qubit splitting(s)•Excitation probability I
~~
pico-second pulses
Pulse width considerations
10 ps 70 GHz
Ion-photon entanglement
2S1/2
2P1/2
12.6 GHz
L.-M. Duan et al., PRA 73, 062324 (2006)
Prepare ion in an arbitrarystate
01 o
excite ion to P state with aπ-polarized picosecond pulse
collect π-polarized photon
01 f R B
• Long Distance• atomic motion insensitivity• No optical interferometric
stability necessary• Hybrid systems• Probabilistic but scalable
Simon and Irvine, PRL, 91, 110405 (2003)
non-local QIP viaphoton coincidence detection
Ion-Ion entanglement
P. Maunz et al., PRL 102, 250502 (2009)
click! click! coincidence detection meansphotons were in state
which heralds the ion-ion state
2121
photons R RB B
21
)2()1()1( )ˆˆ(ˆ ionionzzz I
Photon-mediated entanglement of distant (~1 m) atomic qubits
P. Maunz et al., PRL 102, 250502 (2009)
• Private random numbers
• Bell inequality test
• Quantum teleportation
• Remote entangling gate
S. Olmschenk et al., Science 323, 486 (2010)
S. Pironio et al., Nature 464, 1021 (2010)
D. N. Matsukevich et al., PRL 100, 150404 (2008)
want better photoncollection efficiency
enhanced light collection
12
g
C 2.01.0124
C
Cd
“Decent” cavities G. Guthorlein, et al., Nature 414, 49 (2001)A. Mundt, et al., Phys. Rev. Lett. 89, 103001 (2002)W. Keller,et al., Nature 431, 1075 (2004)
• Time-bin photonic qubit
Insensitive to birefringence,
dispersion
Cavity length free parameter
Time-bin resolving detectors
give other entangled states
p
Light collection: Innsbruck, NIST, Aarhus, Sussex, Saarbrucken, Sandia,
Singapore, Duke, GTRI, Erlangen, MIT, Griffith, Washington, JQI,…
early
photonlate
photon
earlylate
Fastp
Fast
Stimulated Raman transitions
Single photon detuning D
•Spontaneous emission
Optical power = speedand low laser-induceddecoherence
2
I
•Diff. ac Stark shifts 2
I
•Raman Rabi Freq.
I
Raman
Raman Laser Wavelength
2S1/2
2P1/2
12.6 GHz
2P3/2329 nm
370 nm
Δ = 33 THz
Δ
5×10-5
4×10-5
3×10-5
2×10-5
1×10-5
0
Spontaneous emission
340 350 360 370 3800
1 105
2 105
3 105
4 105
.00005
0
P x( )
W x( )
380340 x
spont
340 350 360 370 380
5, 10sponP
Wavelength [nm]
Pulsed laser Raman transitions
Short pulse = large bandwidth•10 ps pulse gives 70 GHz
Short pulse = easy UV•Single-pass SHG, THG, etc.
No need for HF / UV EOM
No need for buildup cavity
Pulsed Raman Transitions:Strong Excitation Regime
Fast.
, temperature,Not very sensitive to
“bang-bang” dynamic decoupling, super-fastcooling (see Machnes hot topic talk), photontime bin qubit, rep rate limited experiments
Strong Pulse Raman Transitions:Rosen-Zener Solution
Nathan Rosen and Clarence Zener (PR 40, 502 (1932)):
xz
tH
ˆ2
)(ˆ
2HF
2sech
2sin pulseHF2pulseo2
ex
TTP
pulseo
sech )(
T
tt
Rabi flopping contrast
Strong Pulse Raman Transitions:pulse duration limited transfer
~70%Single Pulse Rabi Flop
ps 15pulse T
2sech
2sin pulseHF2pulseo2
ex
TTP
Pulsed Raman Transitions:Weak Excitation Regime
X
Requirement:
Rep rate provides spectral sensitivity.
Zqf
f
rep.
qubit
Pulsed Raman Transitions:Weak Pulse Regime
Coherent accumulation of transition amplitude
313q
5.469q
Pulse Train Duration [ms]
Resonance Study for Rabi Flops qf
f
rep.
qubit
5.469q
313q
D. Hayes et al., PRL 104 140501 (2010)
Weak pulse Raman transitions:accessing motion
trapqubit ff
mode-lockedlaser
AOM
trapf
qubitf
rep.f
AOMf
qubitf
Weak pulse Raman transitions:accessing motion
mode-lockedlaser
AOM
trapqubit ff trapqubit ff trapqubit ff trapqubit ff trapqubit ff trapqubit ff trapqubit ff trapqubit ff trapqubit ff trapqubit ff trapqubit ff
standard trapped ion QIP tasksdone with an optical frequency comb
Single qubit operations Sideband cooling
Spin-motion entanglement
AOM Frequency (MHz)200
0,1 1,0 1,1
0,0
1,1 0,1 1,0
201 202 203
N t rep 1
P( )
0.1
0.6
P( )
0.7
0.07.1
Detuning from carrier transition (MHz)
65.1 6.1 6.1 65.1 7.1
Blue SidebandRed Sideband
0.02 0.01 0.00 0.01 0.020.0
0.1
0.2
0.3
0.4
0.5
MHz
P
D. Hayes et al., PRL 104 140501 (2010)
C
1
1
0
2
0
Mølmer-Sørensen gate
Low-decoherence Raman transitions
2S1/2
2P1/2
12.6 GHz
2P3/2
329 nm
370 nm
• Low AC Stark shift (10-4Ω)• Low spon. emiss. (10-5)
• High UV power (4-10 W)
(Emily Edwards hot topics talk Friday)
Mode-Locked Laser Gates
•Raman transitions: Strong excitation regime
fast single qubit operations
working toward fast entanglement
•Raman transitions: Weak excitation regime
your favorite cw tasks done with a comb
low decoherence
•Resonant transitions: excite to the P state
entanglement of distant ions via photons
need increased light collection
Postdocs Kihwan KimLe LuoQudsia QuraishiEmily EdwardsSusan Clark
Grad StudentsDavid HayesDavid HuculRajibul IslamSimcha KorenblitAndrew ManningJonathan MizrahiCrystal SenkoJon SterkShantanu Debnath
UndergradsBrian FieldsKenny LeeAaron Lee
JOINTQUANTUMINSTITUTE
Alumni PeterMaunzStevenOlmschenkDzmitryMatsukevich
P.I.Chris Monroe
Duke
NIST
Singapore