Proposed Measurement of tensor polarizability of ground state Cesium atoms

D. Cho

John K. Stockton, J. M. Geremia

Marshall A. Weissberger

Jason Amini, Harvey Gould

Qing Fan, Pengfei Yang, Da Xu +6 more

Characterizing the trap-light-induced frequency shifts of optical Zeeman transitions is essential for the precise control of the interacting dynamics between optically trapped single atoms and external light fields. The closed hyperfine transition, for example, 6 S 1/2 | F = 4〉 → 6 P 3/2 | F ′ = 5〉 of the cesium (Cs) atom, is commonly used because of its high transition strength. However, within this hyperfine transition line, different Zeeman transitions experience distinct light shifts due to diverse susceptibilities to the light field, which are usually sorted as dynamic scalar, vector, and tensor polarizabilities. Here, we report an efficient method for measuring the light shifts of optical Zeeman transitions using single neutral atoms confined in an optical tweezer (OT). The method employs a weak probe beam together with an auxiliary optical pumping beam to manipulate the atomic population in ground states. In this way, population changes in a specific Zeeman state are mapped onto a different ground-state hyperfine manifold, allowing the optical spectrum of the Zeeman transition to be reconstructed through standard state-detection techniques. By using the method, we demonstrate the spectrum measurement of the open Zeeman transition 6 S 1/2 | F = 4, m F = 4〉 → 6 P 3/2 | F ′ = 5, m F ′ = 3〉 for a single Cs atom trapped in a π polarized OT. We further perform a systematic characterization of the tweezer-induced light shifts for both this open transition and the closed Zeeman transition 6 S 1/2 | F = 4, m F = 4〉 → 6 P 3/2 | F ′ = 5, m F ′ = 5〉 over a wide range of trap depths. The influence of the tensor polarizability in deep trap depths is experimentally observed.

V. V. Tsyganok, D. A. Pershin, E. T. Davletov +2 more

Dipolar atoms have unique properties, making them interesting for laser cooling and quantum simulations. But, due to relatively large orbital momentum in the ground state these atoms may have large dynamic tensor and vector polarizabilities in the ground state. This enables the formation of spin-dependent optical traps. In this paper the real part of tensor and vector dynamic polarizability was experimentally measured and compared to a theoretical simulation. For an optical dipole trap operating around 532.07 nm, tensor polarizability was found to be $\ensuremath{-}145\ifmmode\pm\else\textpm\fi{}53\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}\mathrm{a}.\mathrm{u}.$ and vector polarizability was $680\ifmmode\pm\else\textpm\fi{}240\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}\mathrm{a}.\mathrm{u}.$ The measurements were compared with simulations, which were done based on the known set of levels from a thulium atom. The simulations are in good agreement with experimental results. In addition, losses of atoms from the dipole trap were measured for different trap configurations and compared to the calculated imaginary part of vector and tensor polarizabilities.