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 Cotton in Laboratoire Aimé Cotton 04/12/2013 04/12/2013
Feb 05, 2016
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
3Cold Rydberg atoms in LAC04/12/13 Orsay
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
4Cold Rydberg atoms in LAC04/12/13 Orsay
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
Introduction: Rydberg Introduction: Rydberg atomatom
Zimmerman et al. 1979
Ionization
5Cold Rydberg atoms in LAC04/12/13 Orsay
Introduction: Rydberg Introduction: Rydberg atomatom
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
6Cold Rydberg atoms in LAC04/12/13 Orsay
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
7Cold Rydberg atoms in LAC04/12/13 Orsay
Cs experiment
8Cold Rydberg atoms in LAC04/12/13 Orsay
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
9Cold Rydberg atoms in LAC04/12/13 Orsay
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!
10Cold Rydberg atoms in LAC04/12/13 Orsay
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
11Cold Rydberg atoms in LAC04/12/13 Orsay
Introduction / 1Introduction / 1stst 4-body 4-body schemescheme
• 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
12Cold Rydberg atoms in LAC04/12/13 Orsay
Results / ResonancesResults / Resonances
• Observe the 2-body resonances:
13Cold Rydberg atoms in LAC04/12/13 Orsay
Results / ResonancesResults / Resonances
• Observe the 4-body resonance:
Observe d state :4-body
energy transfer!
Shift Observed
(79.99V/cm)
14Cold Rydberg atoms in LAC04/12/13 Orsay
Results / Density Results / Density dependancedependance
• Observe p → s → d transfer
No residual linearcross-talk from s
15Cold Rydberg atoms in LAC04/12/13 Orsay
Results / Density Results / Density dependancedependance
• Observe p → s → d transfer
p → d transfergoverned by
4-body process4pd
No residual linearcross-talk from s
16Cold Rydberg atoms in LAC04/12/13 Orsay
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
17Cold Rydberg atoms in LAC04/12/13 Orsay
Towards a new experimentOn Ytterbium Rydberg atoms
18Cold Rydberg atoms in LAC04/12/13 Orsay
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
19Cold Rydberg atoms in LAC04/12/13 Orsay
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
20Cold Rydberg atoms in LAC04/12/13 Orsay
Yb experiment planningYb experiment planning
• Trapping practical issue: – MOT capture velocity vc8m/s
– Large divergence of Zeeman slower… 2D MOT!
21Cold Rydberg atoms in LAC04/12/13 Orsay
Yb experiment planningYb experiment planning
• Slowing and trapping simulation:– Longitudinal speed Vs position
Position from Zeeman slower start (m)
Longit
udin
al sp
eed (
m/s
)
22Cold Rydberg atoms in LAC04/12/13 Orsay
Yb experiment planningYb experiment planning
• Slowing and trapping simulation:– Longitudinal speed Vs position
Position from Zeeman slower start (m)
Longit
udin
al sp
eed (
m/s
)
23Cold Rydberg atoms in LAC04/12/13 Orsay
Yb experiment planningYb experiment planning
• Slowing and trapping simulation:– Transverse position Vs longitudinal
position
Position from Zeeman slower start (m)
transv
ers
e p
osi
tion (
m)
24Cold Rydberg atoms in LAC04/12/13 Orsay
Yb experiment planningYb experiment planning
• 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
25Cold Rydberg atoms in LAC04/12/13 Orsay
Thank you for your attention!
26Cold Rydberg atoms in LAC04/12/13 Orsay
27Cold Rydberg atoms in LAC04/12/13 Orsay
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)
28Cold Rydberg atoms in LAC04/12/13 Orsay
Experimental sequenceExperimental sequence
• Fix electric field• Rydberg excitation + delay • Field ionization pulse + detection• Change electric field and repeat…
29Cold Rydberg atoms in LAC04/12/13 Orsay
Results / ResonancesResults / Resonances
• 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
30Cold Rydberg atoms in LAC04/12/13 Orsay
Ytterbium autoinonisationYtterbium autoinonisation
• Total internal energy > ionisation limit– Autoionisation if nl too small:
• Adiabatic loading of large l states:
e-
e-