Thermodynamic modes of a quasiperiodic mobility-edge system in a quantum Otto cycle

TL;DR

This paper explores how a quasiperiodic lattice with a mobility edge can operate as different thermodynamic devices within a quantum Otto cycle, depending on the protocol and parameters, revealing multiple functional modes.

Contribution

It demonstrates the thermodynamic modes of a quasiperiodic system with a mobility edge in a quantum Otto cycle and how to switch between them by tuning system parameters.

Findings

Near-adiabatic protocol supports heater and accelerator modes.

Adiabatic protocol enables heat engine and refrigerator modes.

Mobility-edge systems can realize multiple thermodynamic functions.

Abstract

We investigate thermodynamic operation of a quasiperiodic lattice with an exact mobility edge, described by the Biddle--Das Sarma model. We use this model as the working medium of a quantum Otto cycle and map its operating mode as a function of the hopping-range parameter $p$, the initial and final potential strengths $V_i$ and $V_f$, and two idealized protocols for the isolated strokes. In a near-adiabatic (state-frozen) protocol, where the density matrix is approximately unchanged during the isolated strokes, the cycle supports only two modes: a \emph{heater} and an \emph{accelerator}. In an adiabatic protocol, where level populations are preserved while the spectrum is deformed, two additional modes appear: a \emph{heat engine} and a \emph{refrigerator}. Our results show that mobility-edge systems can realize multiple thermodynamic functions within a single platform and provide guidance for switching between modes by tuning $p$, $V_i$, and $V_f$.