Observation of Free-Space Single-Atom Matterwave Interference

TL;DR

This paper reports the observation of matterwave interference of a single cesium atom in free fall, demonstrating an absolute acceleration sensor with high sensitivity and spatial resolution, and enabling direct measurement of atomic velocity distribution.

Contribution

It presents the first observation of free-space single-atom matterwave interference, showing its potential as a highly sensitive and spatially precise quantum sensor.

Findings

Detected matterwave interference of a single atom in free fall.

Achieved sensitivity to forces at the level of 3.2×10⁻²⁷ N.

Measured the temperature and velocity distribution of a single atom.

Abstract

We observe matterwave interference of a single cesium atom in free fall. The interferometer is an absolute sensor of acceleration and we show that this technique is sensitive to forces at the level of $3.2\times10^{-27}$ N with a spatial resolution at the micron scale. We observe the build up of the interference pattern one atom at a time in an interferometer where the mean path separation extends far beyond the coherence length of the atom. Using the coherence length of the atom wavepacket as a metric, we directly probe the velocity distribution and measure the temperature of a single atom in free fall.