Compensating fictitious magnetic field gradients in optical microtraps by using elliptically polarized dipole light

Abstract

Tightly focused optical dipole traps induce vector light shifts ("fictitious magnetic fields") which complicate their use for single-atom trapping and manipulation. The problem can be mitigated by adding a larger, real magnetic field, but this solution is not always applicable; in particular, it precludes fast switching to a field-free configuration. Here we show that this issue can be addressed elegantly by deliberately adding a small elliptical polarization component to the dipole beam. In our experiments with single ${}^{87}$Rb atoms in a chopped trap, we observe improvements up to a factor 11 of the trap lifetime compared to the standard, seemingly ideal linear polarization. This effect results from a modification of heating processes via spin-state diffusion in state-dependent trapping potentials. We develop Monte-Carlo simulations of the evolution of the atom's internal and motional states and find that they agree quantitatively with the experimental data. The method is general and can be applied in all experiments where the longitudinal polarization component is non-negligible.

6 pages, 5 figures

References in corpus (5)

• Chiral Quantum Optics
• All-Optical Routing of Single Photons by a One-Atom Switch Controlled by a Single Photon
• Cooling a single atom in an optical tweezer to its quantum ground state
• Eliminating light shifts in single-atom optical traps
• Fictitious magnetic field gradients in optical microtraps as an experimental tool for interrogating and manipulating cold atoms

Cited by in corpus (2)

• Point singularity array with metasurfaces
• Portable Real-Time Polarimeter for Partially and Fully Polarized Light