Thermal Global Expansion Coefficient Measurement for a Harmonic Trapped Gas Across Bose-Einstein Condensation

TL;DR

This paper measures the thermal expansion coefficient of a trapped Bose gas around the Bose-Einstein transition, revealing lambda-like behavior and demonstrating the usefulness of global thermodynamic variables in quantum systems.

Contribution

It introduces a method to measure the thermal expansion coefficient of a confined Bose gas using global thermodynamic variables across the phase transition.

Findings

Thermal expansion coefficient exhibits lambda-like shape near transition.

Global thermodynamic variables effectively characterize quantum phase transitions.

The approach offers new insights into thermodynamics of quantum gases.

Abstract

We report the measurement of the global thermal expansion coefficient of a confined Bose gas of $^{87}\rm Rb$ in a harmonic potential around the Bose-Einstein condensation transition temperature. We use the concept of global thermodynamic variables, previously introduced and appropriated for a non-homogeneous system. We observe the behavior of the thermal expansion coefficient above and below the critical temperature showing the lambda-like shape present in superfluid helium. The study demonstrates the potentiality of global thermodynamic variables for the investigation of properties across the critical temperature and a new way to study the thermodynamic properties of the quantum systems.