Gr\"{u}neisen Parameters: origin, identity and quantum refrigeration

TL;DR

This paper explores the origin, identities, and caloric effects of Grüneisen parameters in ultracold quantum gases, revealing their role in quantum refrigeration and critical phenomena through exact solutions.

Contribution

It establishes a new identity among different GPs in quantum gases and demonstrates their application in quantum refrigeration using exact Bethe ansatz solutions.

Findings

Derived analytic expressions for GPs at quantum critical points

Predicted a lowest temperature limit for cooling near quantum phase transitions

Proposed quantum gas interaction ramps as a cooling protocol

Abstract

In solid state physics, the Gr\"{u}neisen parameter (GP), originally introduced in the study of the effect of changing the volume of a crystal lattice on its vibrational frequency, has been widely used to investigate the characteristic energy scales of systems with respect to the changes of external potentials. On the other hand, the GP is little investigated in a strongly interacting quantum gas systems. Here we report on our general results on the origin of GP, new identity and caloric effects in quantum gases of ultracold atoms. We prove that the symmetry of the dilute quantum gas systems leads to a simple identity among three different types of GPs, quantifying caloric effect induced respectively by variations of volume, magnetic field and interaction. Using exact Bethe ansatz solutions, we present a rigorous study of these different GPs and the quantum refrigeration in one-dimensional Bose and Femi gases. Based on the exact equations of states of these systems, we obtain analytic results for the singular behaviour of the GPs and the caloric effects at quantum criticality. We also predict the existence of the lowest temperature for cooling near a quantum phase transition. It turns out that the interaction ramp-up and -down in quantum gases provides a promising protocol of quantum refrigeration in addition to the usual adiabatic demagnetization cooling in solid state materials.