Robust two-dimensional subrecoil Raman cooling by adiabatic transfer in a tripod atomic system

TL;DR

This paper introduces a robust two-dimensional Raman cooling method using adiabatic transfer in a tripod atomic system, achieving ultra-narrow velocity distributions and effective ultra-cold temperatures.

Contribution

It presents a novel 2D Raman cooling technique employing STIRAP pulses in a tripod system, enhancing robustness and efficiency over previous methods.

Findings

Achieved velocity spread down to 0.1 v_rec

Corresponds to an effective temperature of 0.01 T_rec

Method is robust to pulse duration and amplitude variations

Abstract

We demonstrate two-dimensional robust Raman cooling in a four-level tripod system, in which velocity-selective population transfer is achieved by a STIRAP pulse. In contrast to basic 2D Raman cooling with square envelope pulses [Phys. Rev. A 83, 023407 (2011)], the technique presented here allows for a wide variation in the pulse duration and amplitude once the adiabaticity criterion is satisfied. An efficient population transfer together with attaining of a narrow spread of the resonant-velocity group leads to the narrowing of the velocity-distribution spread down to $0.1v_\mathrm{rec}$, corresponding to an effective temperature equal to $0.01 T_\mathrm{rec}$. This robust method opens new possibilities for cooling of neutral atoms.