P. Cheinet, B. Pelle, R. Faoro, A. Zuliani and P. Pillet Laboratoire Aimé Cotton, Orsay (France)...

P. Cheinet, B. Pelle, R. Faoro, A. Zuliani and P. Pillet

Laboratoire Aimé Cotton, Orsay (France)

Cold Rydberg atoms Cold Rydberg atoms

in Laboratoire Aimé Cottonin Laboratoire Aimé Cotton

04/12/201304/12/2013

2Cold Rydberg atoms in LAC04/12/13 Orsay

OutlineOutline

• Introduction: – Rydberg atoms and their

properties

• Cold cesium experiment

• A new experiment on Ytterbium


Introduction: Rydberg Introduction: Rydberg atomatom

• Rydberg atom = highly excited atom

e-

Coolinglevels

|r>

|e>

|f>

E=-1/2n2Rydberg

levels

Failed screening at the core imply quantum defects

Most weight at large r!

1 10 100

-0,2

-0,1

0,0

0,1

0,2

Ene

rgy

or A

mpl

itude

Radius (a.u.)

Potential

23p e- Wavefunction


1 10 100

-0,2

-0,1

0,0

0,1

0,2

Ene

rgy

or A

mpl

itude

Radius (a.u.)

E-field perturbed potential Unperturbed potential e- Wavefunction


Zimmerman et al. 1979

Ionization



0 50 100 150 200-310

-300

-290

-280

-270

Ene

rgy

(cm

-1)

Field (V/cm)

23p3/2

23s

24s

Resonant energy transfer!@ ≈ 80V/cm

ssp 2423232 2/3


Introduction: MotivationsIntroduction: Motivations

→ Possibility to tune interaction type and strength over ORDERS OF MAGNITUDE

→ Selective Field Ionisation (SFI) TOF

→ Many studies:→Dipole blocade→Few and many-body physics→Ultra-cold plasma→2 electron systems


Cs experiment


Experimental setupExperimental setup

• Sequence=MOT,Rydberg,delay,ionisation

Ions extracted throughthe 2 holes to the MCP

Up to 5kV ramp applied between

the 2 central grids

MCP

Delay = 1.5μs (frozen!)Then TOF recorded on MCP


Cs exper./ 4-body Cs exper./ 4-body interactioninteraction

• Two close Förster resonances:→ @ ≈ 79.95V/cm→ @ ≈ 80.4V/cm (quasi-forbidden!)

• A 4-body exchange should be close…

ssp 2423232 2/3

2/52/1 2323242 dps

2/52/3 2323 dp

0 50 100 150 200-310

-300

-290

-280

-270

-260

-250

Ene

rgy

(cm

-1)

Field (V/cm)

23p3/2

23s

24s

23p1/2

23d5/2 TOF!d state is a signatureof 4-body

energy transfer!


Cs exper./ 4-body Cs exper./ 4-body interactioninteraction



ssp 2423232 2/3

2/52/1 2323242 dps

2/52/3 2323 dp


Introduction / 1Introduction / 1stst 4-body 4-body schemescheme



ssp 2423232 2/3

2/52/1 2323242 dps

2/52/3 2323 dp


Results / ResonancesResults / Resonances

• Observe the 2-body resonances:



• Observe the 4-body resonance:

Observe d state :4-body

energy transfer!

Shift Observed

(79.99V/cm)


Results / Density Results / Density dependancedependance

• Observe p → s → d transfer

No residual linearcross-talk from s


Results / Density Results / Density dependancedependance

• Observe p → s → d transfer

p → d transfergoverned by

4-body process4pd

No residual linearcross-talk from s


Conclusion on Cs Exper.Conclusion on Cs Exper.

• Demonstration of a 4-body interaction→Observed 4-body resonant energy transfer→Studied density dependance→Many-body effect at MOT density for n=23

J. Gurian et al., PRL 108, 023005 (2012)

• Other few-body schemes?→RF to restore resonance?

→Spin mixture?

5 6 7 8 9 10

0,00

0,05

0,10

0,15

0,20

f 5/2m

1/2

f 7/2m

5/2

f 7/2m

3/2

ns+

(n-3

)f7/

2m1/

2

ns+(n+1)s

m5/

2+m

1/2

m3

/2+

m1

/2

m3

/2+

m3

/2

Tra

nsfe

r fr

om 3

2p3/

2m3/

2

Electric field (V/cm)

(n+1)p ns (n+1)s

(n-2

)d5

/2m

1/2+

(n+

1)p 3

/2m

3/2

Too many quasi-forbidden

Resonances in Cs


Towards a new experimentOn Ytterbium Rydberg atoms


Ytterbium experimentYtterbium experiment

• Motivation for 2 electron atom:

Coolinglevels

|r>

|e>

|f>

E=-1/2n2Rydberg

levels

e-

Rydberg electronno longer available

for optical manipulation

e-

e- Second electronis available for

cooling/trapping/imaging


Yb experiment planningYb experiment planning

• Yb cooling and trapping

Zeeman Slower399nm

3D MOT556nm

Yb6s6p 1P1

6s2 1S0

5d6s 3D2

5d6s 3D1

6s6p 3P2

6s6p 3P1

6s6p 3P0

398.8 nm

555.6 nm

t = 5.5 ns

t = 875 ns

Efficient but“hot” limit

Weak but“cold” limit



• Trapping practical issue: – MOT capture velocity vc8m/s

– Large divergence of Zeeman slower… 2D MOT!



• Slowing and trapping simulation:– Longitudinal speed Vs position

Position from Zeeman slower start (m)

Longit

udin

al sp

eed (

m/s

)



• Slowing and trapping simulation:– Longitudinal speed Vs position


Longit

udin

al sp

eed (

m/s

)



• Slowing and trapping simulation:– Transverse position Vs longitudinal

position


transv

ers

e p

osi

tion (

m)



• Electrodes and imaging

8 electrodesforming 2 rings

Possibilityto compensate

any field gradient

Holding mechanicsletting all beams pass:16 CF16 + 8 CF40 “in

plane”8 CF16 + 8 CF40 at 45°

2 CF63 at 90°

Under vacuum lens:diffraction limitedimaging of 3µm


Thank you for your attention!



Experimental setupExperimental setup

• Calibrate detection→Direct excitation of each relevant state:

Signal gates

Cross-talk

gatep

s

d

p

s

d

149.4147.3083.0

275.0645.4100.0

082.00645.0016.2

Compute theinversion matrix

to retrieve signal:

(includes ionisation efficiency)


Experimental sequenceExperimental sequence

• Fix electric field• Rydberg excitation + delay • Field ionization pulse + detection• Change electric field and repeat…



• Minimal toy model:→2 or 4 equidistant atoms at distance R→2 or 4 state basis :

→Compute Rabi oscillation to s or d for each field

• Average over distance R :→2 atoms : Erlang nearest neighbour distribution→4 atoms : Erlang distribution cubed

• Average over field inhomogeneity→ ≈ 5V/cm/cm implies 0.1V/cm over sample

'ss

pp

'pd

ss

'''

''

'

sspd

ssss

sspp

pppp


Ytterbium autoinonisationYtterbium autoinonisation

• Total internal energy > ionisation limit– Autoionisation if nl too small:

• Adiabatic loading of large l states:

e-

e-

Date post:	18-Dec-2015
Category:	Documents
Upload:	richard-crawford
View:	221 times
Download:	4 times

P. Cheinet, B. Pelle, R. Faoro, A. Zuliani and P. Pillet Laboratoire Aimé Cotton, Orsay (France)...

Documents