Autoionization of strontium Rydberg states Graham Lochead 01/02/10

Autoionization/experimental overview Outline Autoionization/experimental overview Low n results High n results Graham Lochead 01/02/10

counterpropagating CW Autoionization 4 μs overlapped counterpropagating CW Prepare atoms in ground state 10 ns pulse 408 nm autoionization 461 nm probe 413/420 nm coupling 5s2 5s5p 5sns(d) 5pns(d) 5s1/2 Graham Lochead 01/02/10

Data acquisition Step the Rydberg coupling laser over the transition Collect and integrate the ion signal at each wavelength Fit a Gaussian to the lineshape Extract height and normalise by atom number/pulse energy where appropriate Graham Lochead 01/02/10

Analysis not yet completed Error analysis Analysis not yet completed Major sources of error: Atom number fluctuation Shot-to-shot fluctuation of the pulse laser power Initial estimates of signal error < 15% Graham Lochead 01/02/10

20S Rydberg state lifetime Graham Lochead 01/02/10

20S autoionizing spectrum Graham Lochead 01/02/10

19D Rydberg state lifetime Graham Lochead 01/02/10

19D Rydberg state lifetime Lifetime previously measured to be 740 ± 40 ns Grafström et. al, PRA 27, 947 (1983) Graham Lochead 01/02/10

19D autoionizing spcetrum Shape due to quantum defect difference Cooke et. al, PRL 40, 178 (1977) Graham Lochead 01/02/10

Total Rydberg ionization Were able to completely ionize Rydbergs Loss fraction calculated – total Rydberg number Can calculate Rydberg-Rydberg ionization Graham Lochead 01/02/10

56D lifetime measurements 413 power (mW) Lifetime (μs) 5 16.3 ± 0.9 10 80 ± 6 15 98 ± 5 20 109 ± 19 Possibly caused by high angular momentum state mixing Dutta et. al, PRL 86, 3993 (2001) Graham Lochead 01/02/10

56D autoionizing spectrum Graham Lochead 01/02/10

56D density effects Graham Lochead 01/02/10

Follow up experiments without pulse laser Explain the 56D data Outlook Finish error analysis Follow up experiments without pulse laser Explain the 56D data Graham Lochead 01/02/10