Imaging a single atom in a time-of-flight experiment

TL;DR

This paper demonstrates high-resolution imaging of a single atom's time-of-flight expansion, enabling precise temperature measurement and calibration of imaging systems for few-atom experiments.

Contribution

It introduces a method for imaging a single atom after release from a trap with near 1 micrometer resolution, linking spatial expansion to temperature measurement.

Findings

Single atom position resolved with ~1 micrometer accuracy.

Time-of-flight expansion matches independent temperature measurements.

Method aids calibration of imaging systems for few-atom experiments.

Abstract

We perform fluorescence imaging of a single 87Rb atom after its release from an optical dipole trap. The time-of-flight expansion of the atomic spatial density distribution is observed by accumulating many single atom images. The position of the atom is revealed with a spatial resolution close to 1 micrometer by a single photon event, induced by a short resonant probe. The expansion yields a measure of the temperature of a single atom, which is in very good agreement with the value obtained by an independent measurement based on a release-and-recapture method. The analysis presented in this paper provides a way of calibrating an imaging system useful for experimental studies involving a few atoms confined in a dipole trap.