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Excited state spatial distributions

Excited state spatial distributions. Outline. Rydberg spatial distribution Locked coupling laser spectra Preliminary spatial distributions. Motivation. Ground state. Excited state. Interaction energy. Column density (arb. units). Separation. Distance (microns). Experimental procedure.

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Excited state spatial distributions

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  1. Excited state spatial distributions Graham Lochead 20/06/11

  2. Outline Graham Lochead 20/06/11 • Rydberg spatial distribution • Locked coupling laser spectra • Preliminary spatial distributions

  3. Motivation Graham Lochead 20/06/11 Ground state Excited state Interaction energy Column density (arb. units) Separation Distance (microns)

  4. Experimental procedure Graham Lochead 20/06/11 Automatic translation stage Lens setup

  5. Autoionization Graham Lochead 20/06/11 • Allows independent Rydberg excitation and investigation • Ion detection is very sensitive 5s2 5s5p 5sns(d) 5pns(d) 5s1/2+

  6. Ion spectrum experimental setup Graham Lochead 20/06/11 408 pulse (1 μs) Probe + Coupling (1 μs) Electric field pulse (5 μs) MOT + Zeeman MOT + Zeeman Time Repeat • Probe frequency stepped • Camera image taken for atom number • 100 ns between excitation pulses • 408 not at focus

  7. 56D spectrum Graham Lochead 20/06/11 Integrate to get each point Example ion signal Example Rydberg spectrum

  8. MOT coil turn off Graham Lochead 20/06/11 Varying time between MOT coil switch off and excitation beams • Zeeman effect • Previously did not • have the resolution • to see this splitting • Set Δt to be 400 μs • to avoid this

  9. Ion spectrum characterisation Graham Lochead

  10. Translation experiment setup Graham Lochead 20/06/11 408 pulse (1 μs) Probe + Coupling (1 μs) Electric field pulse (5 μs) MOT + Zeeman MOT + Zeeman Time Repeat • Probe frequency set to max ion signal • 408 is at focus • Translation stage stepped

  11. Translation signal-to-noise Graham Lochead 20/06/11 • Focused 408 addresses few atoms • Autoionising signal may be small • Spontaneous ionization is a problem • D states are repulsive

  12. Chi-squared fit Graham Lochead 20/06/11 Average of three translation runs with standard error Gaussian fit to all data Do not expect Rydberg Blockade at this n or density

  13. Reaching Rydberg Blockade Graham Lochead Two ways to reach blockade: • Increase n • Increase density

  14. Higher n error signals Graham Lochead 20/06/11 Main constraint for higher n is laser locking signal n-3

  15. Repump lasers Graham Lochead 20/06/11 5s6s 3S1 Current cooling scheme has leak 679 nm 707 nm 5s5p 1P1 5s4d 1D2 3P2 3P1 461 nm 3P0 5s5p Repumping increases density by approximately order of magnitude 5s2 1S0

  16. Summary / Outlook Graham Lochead 20/06/11 • Repeatable ion spectra • Preliminary spatial distributions • Need to increase density

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