1. Microwave Transitions Between Pair States Composed of Two Rb Rydberg Atoms Jeonghun Lee Advisor: Tom F. Gallagher Department of Physics, University of Virginia 1

2. Background was recently observed The transition is allowed because dipole-dipole induced configuration interaction between and states admixes some of the latter state into the former 2

3. With configuration interaction, state for R<∞ can be written as where 3

4. The coupling between and states in lowest order is: Since and the dipole matrix elements are proportional to, 4

5. Yinan Yu, Hyunwook Park, and T. F. Gallagher Phys. Rev. Lett. 111, 173001 (2013) 5 Previous Result

6. 6 Yinan Yu, Hyunwook Park, and T. F. Gallagher Phys. Rev. Lett. 111, 173001 (2013)

7. Experiment Overview We use magneto-optical trap and optical excitation to make a cold sample of Rb Rydberg atoms We use microwave to excite Rydberg atoms to different states We use Field ionization to ionize the Rydberg atoms and MCP detector collect data ns,np,nd 7

8. 8 Observed resonances for a range of relative microwave field amplitudes

9. 9 Observed resonances for a range of Rydberg atom densities

10. Resonance frequency & Power shift of the resonance frequency Extrapolating the points back to zero microwave power allows us to determine resonance frequency of the transition 10

11. nCalculated (GHz) Meausred (GHz) Differences (MHz) 3449.897949.8984 0.5 3545.916045.9150 1.0 3642.344042.3410 3.0 3739.131039.1288 2.2 3836.233336.2308 2.5 3933.613333.6117 1.6 4031.238731.2364 2.3 4129.081929.0792 2.7 4227.117927.1132 4.7 Transition frequency for 11 nCalculated (GHz) Meausred (GHz) Differences (MHz) 3449.618349.6174 0.9 3545.659845.6596 0.2 3642.108842.1062 2.6 3738.914438.9119 2.5 3836.033536.0308 2.7 3933.428633.4277 0.9 4031.067631.0662 1.4 4128.922928.9206 2.3 4226.970226.9682 2.0

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15. 15 Acknowledgement Dr. Tom Gallagher Grad students & postdoc researchers at my lab Air Force Office of Scientific Research