Spatially Resolved Temperature Measurement Using Rydberg Doppler Broadening Thermometry

TL;DR

This paper presents a novel technique for spatially resolved temperature measurement in cold atoms using Rydberg Doppler broadening, enabling localized temperature and velocity correlation measurements with high precision.

Contribution

The authors introduce a perpendicular laser configuration for Rydberg Doppler thermometry that allows for localized temperature measurement within a cold atom cloud.

Findings

Achieved temperature resolution on the order of nanokelvin.

Enabled measurement of position-velocity correlations in cold atoms.

Demonstrated local temperature measurement in a magneto-optical trap.

Abstract

We demonstrate a technique for spatially resolved temperature measurement utilizing Rydberg Doppler broadening thermometry. This method employs two focused laser beams arranged perpendicularly to excite laser-cooled atoms from the ground state to a Rydberg state via two photon absorption process. Temperature is obtained through the Doppler broadening of the spectral line. The perpendicular configuration allows for selective probing of a specific position within the atomic cloud, enabling localized temperature measurement. This technique, in principle, offers a temperature resolution on the order of \SI{}{\nano\kelvin}, attributed to the exceptionally narrow natural linewidth of the involved rubidium Rydberg transition line. Furthermore, the setup enables the measurement of position-velocity correlations within the cold atom ensemble. The velocity information is extracted through the Doppler shift, whereas the spatial information is inferred from the arrival time of ions detected by a channel electron multiplier detector. We use our method to measure the local temperature in a magneto-optical trap.