Cooling bosons by dimensional reduction

TL;DR

This paper demonstrates a highly sensitive thermometry method for strongly interacting Bose gases in reduced dimensions, revealing significant temperature variations and potential cooling effects due to dimensional reduction and interactions.

Contribution

The study introduces a novel thermometry technique based on correlation decay sensitivity, enabling temperature measurement in low-dimensional Bose gases with high precision.

Findings

Temperature can vary significantly when transitioning from 3D to 1D or 2D systems.

One-dimensional Bose gases can reach temperatures much lower than the initial 3D temperature.

Dimensional reduction combined with strong interactions can lead to effective cooling of the system.

Abstract

Cold atomic gases provide a remarkable testbed to study the physics of interacting many-body quantum systems. They have started to play a major role as quantum simulators, given the high degree of control that is possible. A crucial element is given by the necessarily non-zero temperature. However cooling to the required ultralow temperatures or even simply measuring the temperature directly on the system can prove to be very challenging tasks. Here, we implement thermometry on strongly interacting two- and one-dimensional Bose gases with high sensitivity in the nano-Kelvin temperature range. Our method is aided by the fact that the decay of the first-order correlation function is very sensitive to the temperature when interactions are strong. We find that there may be a significant temperature variation when the three-dimensional quantum gas is cut into two-dimensional slices or into one-dimensional tubes. Strikingly, the temperature for the one-dimensional case can be much lower than the initial temperature. Our findings show that this decrease results from the interplay of dimensional reduction and strong interactions.