Nearly nondestructive thermometry of labeled cold atoms and application to isotropic laser cooling

TL;DR

This paper introduces a nearly nondestructive thermometry method for cold atoms, enabling precise temperature measurement and application to isotropic laser cooling, with confirmed sub-Doppler cooling features and improved cooling performance using hollow beams.

Contribution

The paper presents a novel nondestructive thermometry technique for cold atoms and demonstrates its application to isotropic laser cooling with enhanced cooling efficiency.

Findings

Confirmed sub-Doppler cooling features in isotropic laser cooling.

Demonstrated nearly lossless detection via cycling transition.

Enhanced cooling performance with hollow beam injection.

Abstract

We have designed and implemented a straightforward method to deterministically measure the temperature of the selected segment of a cold atom ensemble, and we have also developed an upgrade in the form of nondestructive thermometry. The essence is to monitor the thermal expansion of the targeted cold atoms after labeling them through manipulating the internal states, and the nondestructive property relies upon the nearly lossless detection via driving a cycling transition. For cold atoms subject to isotropic laser cooling, this method has the unique capability of addressing only the atoms on the optical detection axis within the enclosure, which is exactly the part we care about in major applications such as atomic clock or quantum sensing. Furthermore, our results confirm the sub-Doppler cooling features in isotropic laser cooling, and we have investigated the relevant cooling properties. Meanwhile, we have applied the recently developed optical configuration with the cooling laser injection in the form of hollow beams, which helps to enhance the cooling performance and accumulate more cold atoms in the central regions.