Multiphoton microwave ionization of Li Rydberg atoms

Transcription

1 Multiphoton microwave ionization of Li Rydberg atoms Josh Gurian Professor Thomas Gallagher April 28, 2008

2 Outline khz Dye Laser Project Experimental Apparatus Ionization Steps

3 Rydberg atom overview W = 1 2n 2 r n 2 Lifetime n 3 ω kepler 1/n 3 V coulomb = 1 z z V

4 Rydberg atom overview W = 1 2n 2 r n 2 Lifetime n 3 ω kepler 1/n 3 V = 1 z + Ez -6 z V

5 Field Ionization V z V = 1 z + Ez dv dz =

6 Field Ionization V 2 z V = 1 z + Ez dv dz = 0 V = 2 E -6

7 Field Ionization V 2 z V = 1 z + Ez dv dz = 0 V = 2 E E = W 2 4-6

8 Field Ionization V 2 z E = W 2 4 W = n 2 2 nke -6

9 Field Ionization V 2 z E = W 2 4 W = n 2 2 nke E = 1 9n 4-6

10 Scaled Frequency Important characteristic: ω 0 = Previous work for ω 0 1: ω ω kepler = ωn 3 van Leeuwen et al., PRL 55 (1985) Jensen et al., PRL 62 (1989) Pillet et al., PRA 30 (1984) Noel et al., PRA 62 (2000)

11 Microwave Ionization Pillet et al., PRA 30 (1984)

12 Photoionization limit? What happens as we approach the photoionization limit, when ω 0 n?

13 Cartoon MW Ionization Cartoon Normalized electron signal (arb) Binding energy (GHz)

14 Cartoon MW Ionization Cartoon Normalized electron signal (arb) Binding energy (GHz)

15 Cartoon MW Ionization Cartoon Normalized electron signal (arb) No MW 0.11 mv/cm Binding energy (GHz)

16 Cartoon MW Ionization Cartoon Normalized electron signal (arb) No MW 0.11 mv/cm 0.67 mv/cm Binding energy (GHz)

17 Cartoon MW Ionization Cartoon Normalized electron signal (arb) No MW 0.11 mv/cm 0.67 mv/cm 1.83 mv/cm Binding energy (GHz)

18 Cartoon MW Ionization Cartoon Normalized electron signal (arb) No MW 0.11 mv/cm 0.67 mv/cm 1.83 mv/cm 3.8 mv/cm Binding energy (GHz)

19 Cartoon MW Ionization Cartoon Normalized electron signal (arb) No MW 0.11 mv/cm 0.67 mv/cm 1.83 mv/cm 3.8 mv/cm 6.6 mv/cm Binding energy (GHz)

20 Outline khz Dye Laser Project Experimental Apparatus khz Dye Laser Project Experimental Apparatus Ionization Steps

21 khz Dye Laser Project Experimental Apparatus Coherent Evolution-30 Nd:YLF Laser Normalized photodiode signal (arb) Relative time (ns)

22 khz Dye Laser Project Experimental Apparatus Coherent Evolution-30 Nd:YLF Laser 1st Pulse: 20ns 2nd Pulse: 35ns 3rd Pulse: 41ns Normalized photodiode signal (arb) First Pulse Second Pulse Third Pulse Relative time (ns)

23 Laser Setup khz Dye Laser Project Experimental Apparatus Dye Laser Amp Dye Laser BS Dye Laser 1 Dump 3 PBS PC PBS BS 2 Pump Laser PC

24 khz Dye Laser Project Experimental Apparatus

25 khz Dye Laser Project Experimental Apparatus

26 Timing khz Dye Laser Project Experimental Apparatus Laser Pulses ns MW Pulse Field Pulse 0-2V/cm time (ns)

27 khz Dye Laser Project Experimental Apparatus

28 Outline Ionization Steps khz Dye Laser Project Experimental Apparatus Ionization Steps

29 Cartoon Ionization Steps MW Ionization Cartoon Normalized electron signal (arb) No MW 0.11 mv/cm 0.67 mv/cm 1.83 mv/cm 3.8 mv/cm 6.6 mv/cm Binding energy (GHz)

30 Ionization Steps Microwave Ionization Steps - Powers 200ns MW pulse at GHz Normalized electron signal (arb) V/cm 0.25 V/cm 0.5 V/cm 1 V/cm Binding energy (GHz)

31 Pulsewidths Ionization Steps Various MW pulsewidths at GHz, 1 V/cm Normalized electron signal (arb) 100ns 200ns 300ns 400ns 500ns Binding energy (GHz)

32 Ionization Rate Ionization Steps MW photons from ionization limit Relative remaining population (arb) V/cm -2 db -4 db -6db -8db -10db pulsewidth (ns)

33 Theoretical Predictions Ionization Steps Γ exp (n 360, E 0.8V /cm, 50ns) = s 1 Hoogenraad and Noordam, PRA 57 (1998): < n r n > n 3/2 n 3/2 ω 5/3 We can calculate the ionization rate: Γ = 2π < n r ɛ > E 2 Γ(n = 360, E = 0.8V /cm) = s 1 Γ(n = 360, E = 0.2V /cm) = s 1

34 Bias Field Ionization Steps Bias voltages on top plate for 200ns MW pulse at GHz, 1 V/cm Normalized electron signal (arb) 0 V/cm 8.5 mv/cm 17 mv/cm 85 mv/cm Binding energy (GHz)

35 Ionization Steps E = 1/9n 4 Laser Pulses Field Pulse time (ns)

36 Ionization Steps without MW pulse 400 Relative Time (ns) Binding energy (GHz) J. Gurian Multiphoton MW Ionization 0

37 Ionization Steps E = 1/9n 4 Laser Pulses 200 ns MW Pulse Field Pulse 1 V/cm time (ns)

38 Ionization Steps with 200ns GHz 1 V/cm MW pulse 400 Relative Time (ns) Binding energy (GHz) J. Gurian Multiphoton MW Ionization 0

39 Summary Ionization Steps to Rydberg field ionization Overview of microwave ionization Experiment setup First results for microwave multiphoton ionization of Rydberg Li atoms

40 Thanks Ionization Steps Professor Tom Gallagher Dr. Haruka Maeda Dr. Ed Shuman Paul Tanner Jianing Han Jirakan Nunkaew Don Norum Hyunwook Park National Science Foundation

41 Ionization Steps Comparison with 200ns GHz 10dbm MW pulse Relative Time (ns) Relative Time (ns) without MW pulse Binding energy (GHz) J. Gurian Binding energy (GHz) Multiphoton MW Ionization 0

42 Dye laser output Ionization Steps 1 671nm Dye Laser Pulse 813nm Dye Laser Pulse 615nm Dye Laser Pulse 0.8 Normalized photodiode signal (arb) Time (nanoseconds)

43 Atomic Conductance Ionization Steps Schelle, Delande, and Buchleitner: