1. Millimeter Wave Spectroscopy of Cold 85 Rb Atoms JIANING HAN, YASIR JAMIL, PAUL TANNER, DON NORUM, T. F. GALLAGHER University of Virginia Supported by: the Air Force Office of Scientific Research

2. Outline Motivation Quantum defects measurements Population transfer Conclusion

3. Motivation Cold rydberg atoms Artificial amorphous solids Automatically evolve into plasma Microwave High resolution spectral probe Manipulate atoms [1] H. Maeda, et al., Science 307, 1757 (2005) Cold rydberg atoms Artificial amorphous solids Automatically evolve into plasma Microwave High resolution spectral probe Manipulate atoms [1] H. Maeda, et al., Science 307, 1757 (2005)

4. Theory Hydrogen atom: Core polarizationOrbital Penetration Alkali atoms:

5. The energy diagram and timing 0 2 4 6 8 T(μs) 480nm dye laser pulse Microwave pulse Field ionization ramp Timing ~480nm 5p 3/2 (n+2)d 5/2 nf Microwave Energy diagram J 5/2 7/2

6. Selective Field Ionization (SFI) Time Voltage Field ionization ramp Oscilloscope trace

7. A typical resonance The line width is about the transform limit of a 5 μs microwave pulse The side peaks are the off resonance excitation of a π pulse The 32d 5/2 -30f 7/2 resonance. The microwave pulse length is about 5μs. 200kHz

8. Results The quantum defects of f 5/2,7/2 states were fitted to the function: The improved and previous quantum defects are listed in table 1

9. Results If we fit the fine structure intervals between the f 5/2 and f 7/2 by the following function: A = -157.68(25)GHz; B = 1.917(13)THz. The fine structure plots. The small plot is a magnified plot for n*>29. The first two points are cited from: J.Farley and R. Gupta, PRA 15, 1952(1977)

10. Adiabatic Rapid Passage (ARP) Floquet theory [2] To get a large population transfer: Ω [2] J. H. Shirley, Phys. Rev. 138, B979(1965)

11. Population Transfer Time ( μs ) 012 480nm dye laser pulse Chirped microwave pulse Field ionization ramp 38d 36f

12. Conclusion Using microwave as a sensitive spectral probe, we measured the quantum defects of f 5/2,7/2 states. Using a chirped microwave pulse, we can transfer about 80% atoms from d states to f states.