Sensitive Absorption Imaging of Single Atoms in Front of a Mirror

TL;DR

This paper demonstrates that standing-wave absorption imaging significantly enhances sensitivity for detecting single ultracold atoms, especially near reflective surfaces like atom chips, by optimizing imaging parameters and accounting for noise.

Contribution

It introduces a novel standing-wave imaging configuration for ultracold atoms, showing improved sensitivity over traditional methods through simulations and noise analysis.

Findings

Standing-wave imaging improves signal-to-noise ratio by 1.7 times.

Optical density depends solely on the numerical aperture.

Optimal imaging parameters are identified considering noise sources.

Abstract

In this paper we show that the sensitivity of absorption imaging of ultracold atoms can be significantly improved by imaging in a standing-wave configuration. We present simulations of single-atom absorption imaging both for a travelling-wave and a standing-wave imaging setup, based on a scattering approach to calculate the optical density of a single atom. We find that the optical density of a single atom is determined only by the numerical aperture of the imaging system. We determine optimum imaging parameters, taking all relevant sources of noise into account. For reflective imaging we find an improvement of 1.7 in the maximum signal-to-noise ratio can be achieved. This is particularly useful for imaging in the vicinity of an atom chip, where a reflective surface is naturally present.