In situ imaging of the thermal de Broglie wavelength in an ultracold Bose gas

TL;DR

This paper presents the first in situ imaging of density fluctuations at the thermal de Broglie wavelength in an ultracold Bose gas, revealing atom bunching and correlation enhancements using quantum gas microscopy.

Contribution

It introduces a novel in situ imaging technique to observe density fluctuations at the thermal de Broglie wavelength in ultracold gases, enabling studies of many-body systems and phase transitions.

Findings

Observed 30% enhancement of second-order correlation function.

Detected atom bunching in a quasi-2D Bose gas.

Demonstrated spatial and thermal dependence of correlations.

Abstract

We report the first in situ observation of density fluctuations on the scale of the thermal de Broglie wavelength in an ultracold gas of bosons. Bunching of $^{87}$Rb atoms in a quasi two-dimensional system is observed by single-atom imaging using a quantum gas microscope. Compared to a classical ensemble, we observe a 30 percent enhancement of the second-order correlation function. We show the spatial and thermal dependence of these correlations. The reported method of detecting in situ correlations can be applied to interacting many-body systems and to the study of critical phenomena near phase transitions.