Measuring Polarizability with an Atom Interferometer

1. Measuring Polarizability with an Atom Interferometer Melissa Revelle

2. Overview • The Importance of Atomic Polarizability • Our Interferometer • Modeling the Experiment • Progress • Future

3. Why Atomic Polarizability? • Relates to • Van der Waals forces • Black body shifts for atomic clocks • Depths of optical dipole traps for atoms • Precision of αNa = 0.5% • Precision of αK = 2%

4. Using Phase Shift to Find Polarizability Detector Atom beam 1G 2G 3G

5. Using Phase Shift to Find Polarizability Detector Atom beam x 1G 2G 3G

6. Using Phase Shift to Find Polarizability Detector Atom beam x 1G 2G 3G

7. Original Data • Atom flux at each grating position is recorded • Polarizability relates to this phase shift

8. Phase Shifts in an Atom Interferometer • From the Schrödinger equation for an atom beam, we get: • The total phase shift becomes:

9. The Electric Field Gradient Region Atom beams x z y y x

10. The Electric Field Gradient Region x z y y x

11. Finding the Equipotential Surfaces and Charge Density • For an ideal wire and an image wire: Atom beams y0 R g l d z y x

12. Creating the Model • Integrate along a path in the x direction to get the phase shift. • L=distance from 1G to gradient region a=grating period

13. Fitting the Data Data Fit Function Phase Shift [rad] • The model for the E-field and phase shift is used as a fit function Distance from Cylinder [mm]

14. Summary • We can precisely measure polarizability using atom interferometry. • The electric field must be accurate. • Velocity distribution is important

15. Current and Future Progress • Improve precision polarizability of sodium and potassium to better than 1% • Measure the polarizability tensor components of molecules.

16. References A.Salop, E. Pollack, and B. Bederson, Phys. Rev. 124, 1431 (1961) L. de Broglie, Ann. Phys. (Paris) 3, 22 (1925) R. Molof, H. Schwartz, T. Miller, and B. Bederson, Phys. Rev. A 10, 1131 (1974)