Self-Bayesian Aberration Removal via Constraints for Ultracold Atom Microscopy

TL;DR

This paper introduces a digital aberration correction method for high-resolution quantum microscopy using low-cost optics, enabling near-optimal imaging of ultracold atoms without additional hardware.

Contribution

The authors develop a novel, hardware-free digital aberration correction technique applicable to various imaging strategies in quantum microscopy.

Findings

Nearly full NA recovered with digital correction

Effective aberration removal demonstrated with phase contrast imaging

Reduction of photon shot noise in quantum measurements

Abstract

High-resolution imaging of ultracold atoms typically requires custom high numerical aperture (NA) optics, as is the case for quantum gas microscopy. These high NA objectives involve many optical elements each of which contributes to loss and light scattering, making them unsuitable for quantum back-action limited "weak" measurements. We employ a low cost high NA aspheric lens as an objective for a practical and economical-although aberrated-high resolution microscope to image ${^{87}\mathrm{Rb}}$ Bose-Einstein condensates. Here, we present a novel methodology for digitally eliminating the resulting aberrations that is applicable to a wide range of imaging strategies and requires no additional hardware. We recover nearly the full NA of our objective, thereby demonstrating a simple and powerful digital aberration correction method for achieving optimal microscopy of quantum objects. This reconstruction relies on a high quality measure of our imaging system's even-order aberrations from density-density correlations measured with differing degrees of defocus. We demonstrate our aberration compensation technique using phase contrast imaging, a dispersive imaging technique directly applicable to quantum back-action limited measurements. Furthermore, we show that our digital correction technique reduces the contribution of photon shot noise to density-density correlation measurements which would otherwise contaminate the desired quantum projection noise signal in weak measurements.