Heat capacities of thermally manipulated mechanical oscillator at strong coupling

TL;DR

This paper investigates the thermodynamic properties of solid-state optomechanical oscillators under strong coupling, revealing anomalous heat capacity behaviors and their implications for quantum thermodynamics experiments.

Contribution

It introduces a model linking temperature-dependent energy levels to strong coupling effects in mechanical oscillators, highlighting novel thermodynamic phenomena.

Findings

Localization and purification induced by heating

Negativity of generalized heat capacities

Capacities as witnesses of non-linearity in energy levels

Abstract

Coherent quantum oscillators are basic physical systems both in quantum statistical physics and quantum thermodynamics. Their realizations in lab often involve solid-state devices sensitive to changes in ambient temperature. We represent states of the solid-state optomechanical oscillator with temperature-dependent frequency by equivalent states of the mechanical oscillator with temperature-dependent energy levels. We interpret the temperature dependence as a consequence of strong coupling between the oscillator and the heat bath. We explore parameter regimes corresponding to anomalous behavior of mechanical and thermodynamic characteristics as a consequence of the strong coupling: (i) The localization and the purification induced by heating, and (ii) the negativity of two generalized heat capacities. The capacities can be used to witness non-linearity in the temperature dependency of the energy levels. Our phenomenological experimentally-oriented approach can stimulate development of new optomechanical and thermomechanical experiments exploring basic concepts of strong coupling thermodynamics.