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Cold Rydberg atoms in Laboratoire Aimé Cotton

Cold Rydberg atoms in Laboratoire Aimé Cotton. P. Cheinet , B. Pelle, R. Faoro, A. Zuliani and P. Pillet Laboratoire Aimé Cotton, Orsay (France). 04/12/2013. Outline. Introduction: Rydberg atoms and their properties Cold cesium experiment A new experiment on Ytterbium.

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Cold Rydberg atoms in Laboratoire Aimé Cotton

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  1. Cold Rydberg atoms in Laboratoire Aimé Cotton P. Cheinet, B. Pelle, R. Faoro, A. Zuliani and P. Pillet Laboratoire Aimé Cotton, Orsay (France) 04/12/2013

  2. Outline • Introduction: • Rydberg atoms and their properties • Cold cesium experiment • A new experiment on Ytterbium

  3. Introduction: Rydberg atom • Rydberg atom = highly excited atom Failed screening at the core imply quantum defects e- Rydberg levels |r> |e> |f> E=-1/2n2 Cooling levels Most weight at large r!

  4. Introduction: Rydberg atom Ionization Zimmerman et al. 1979

  5. Introduction: Rydberg atom 24s 23p3/2 Resonant energy transfer! @ ≈ 80V/cm 23s

  6. Introduction: 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

  7. Cs experiment

  8. Experimental setup • Sequence=MOT,Rydberg,delay,ionisation Ions extracted through the 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

  9. Cs exper./ 4-body interaction • Two close Förster resonances: • @ ≈ 79.95V/cm • @ ≈ 80.4V/cm (quasi-forbidden!) • A 4-body exchange should be close… 23d5/2 TOF! d state is a signature of 4-body energy transfer! 24s 23p3/2 23p1/2 23s

  10. Cs exper./ 4-body interaction • Two close Förster resonances: • @ ≈ 79.95V/cm • @ ≈ 80.4V/cm (quasi-forbidden!) • A 4-body exchange should be close…

  11. Introduction / 1st 4-body scheme • Two close Förster resonances: • @ ≈ 79.95V/cm • @ ≈ 80.4V/cm (quasi-forbidden!) • A 4-body exchange should be close…

  12. Results / Resonances • Observe the 2-body resonances:

  13. Results / Resonances • Observe the 4-body resonance: Observe d state : 4-body energy transfer! Shift Observed (79.99V/cm)

  14. Results / Densitydependance • Observe p → s → d transfer No residual linear cross-talk from s

  15. Results / Densitydependance • Observe p → s → d transfer No residual linear cross-talk from s p → d transfer governed by 4-body process

  16. 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? • Too many • quasi-forbidden • Resonances in Cs

  17. Towards a new experiment On Ytterbium Rydberg atoms

  18. Ytterbium experiment • Motivation for 2 electron atom: e- e- e- • Rydberg electron • no longer available • for optical manipulation Rydberg levels |r> |e> |f> E=-1/2n2 • Second electron • is available for • cooling/trapping/imaging Cooling levels

  19. Yb experiment planning • Yb cooling and trapping 6s6p 1P1 t = 5.5 ns 5d6s 3D2 Yb 5d6s 3D1 Zeeman Slower 399nm 398.8 nm • Efficient but • “hot” limit 6s6p 3P2 6s6p 3P1 t = 875 ns 6s6p 3P0 555.6 nm • Weak but • “cold” limit 3D MOT 556nm 6s21S0

  20. Yb experiment planning • Trapping practical issue: • MOT capture velocity vc8m/s • Large divergence of Zeeman slower… 2D MOT!

  21. Yb experiment planning • Slowing and trapping simulation: • Longitudinal speed Vs position • Longitudinal speed (m/s) • Position from Zeeman slower start (m)

  22. Yb experiment planning • Slowing and trapping simulation: • Longitudinal speed Vs position • Longitudinal speed (m/s) • Position from Zeeman slower start (m)

  23. Yb experiment planning • Slowing and trapping simulation: • Transverse position Vs longitudinal position • transverse position (m) • Position from Zeeman slower start (m)

  24. Yb experiment planning • Electrodes and imaging • Holding mechanics • letting all beams pass: • 16 CF16 + 8 CF40 “in plane” • 8 CF16 + 8 CF40 at 45° • 2 CF63 at 90° • 8 electrodes • forming 2 rings • Possibility • to compensate • any field gradient • Under vacuum lens: • diffraction limited • imaging of 3µm

  25. Thank you for your attention!

  26. Experimental setup • Calibrate detection • Direct excitation of each relevant state: Signal gates Cross-talk Compute the inversion matrix to retrieve signal: (includes ionisation efficiency)

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

  28. Results / 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

  29. Ytterbium autoinonisation • Total internal energy > ionisation limit • Autoionisation if nl too small: • Adiabatic loading of large l states: e- e-

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