Irreversibility in a unitary finite-rate protocol: The concept of internal friction

TL;DR

This paper investigates quantum internal friction in a spin-1/2 system driven by a transverse magnetic field, analyzing energy irreversibility during finite-time adiabatic processes using quantum relative entropy.

Contribution

It introduces a quantitative analysis of quantum internal friction in a simple system, exploring how protocol time and control schemes affect irreversibility and potential for frictionless transformations.

Findings

Internal friction exhibits non-monotonic behavior with respect to protocol duration.

Almost frictionless finite-time transformations are possible under certain control schemes.

Quantum relative entropy effectively quantifies energy irreversibility in the system.

Abstract

The concept of internal friction, a fully quantum mechanical phenomena, is investigated in a simple, experimentally accessible quantum system in which a spin-1/2 is driven by a transverse magnetic field in a quantum adiabatic process. The irreversible production of the waste energy due to the quantum friction is quantitatively analyzed in a forward-backward unitary transform of the system Hamiltonian by using the quantum relative entropy between the actual density matrix obtained in a parametric transformation and the one in a reversible adiabatic process. Analyzing the role of total transformation time and the different pulse control schemes on the internal friction reveal the non-monotone character of the internal friction as a function of the total protocol time and the possibility for almost frictionless solutions in finite-time transformations.