Towards Nonlinear Quantum Thermodynamics

TL;DR

This paper explores the potential of nonlinear quantum thermodynamic devices, highlighting their unique capabilities, advantages over linear devices, and the challenges in harnessing nonlinearity at the quantum level for practical applications.

Contribution

It introduces new schemes for nonlinear thermodynamic devices, compares linear and nonlinear transformations, and discusses deterministic versus probabilistic methods for achieving quantum nonlinearity.

Findings

Nonlinear TD devices can operate coherently without dissipation.

They outperform linear devices in certain thermodynamic tasks.

Deterministic methods can achieve giant nonlinearity at the few-photon level.

Abstract

We have recently put forth several schemes of unconventional, nonlinearly-enabled thermodynamic (TD) devices that can operate in either the classical or the quantum domain by transforming thermal-state input in multiple uncorrelated modes into non-gaussian state output in selected modes: a four-mode Kerr-nonlinear interferometer that acts as a heat engine; two coupled Kerr-nonlinear Mach-Zehnder interferometers that act as a phase microscope with unprecedented phase resolution; and a noise sensor that can distinguish between unknown nonlinear quantum processes. These schemes reveal the unique merits of nonlinear TD devices: their ability to act in an autonomous, fully coherent, dissipationless fashion, unlike their conventional counterparts. Here we present the opportunities and challenges facing this new paradigm of nonlinear (NL) quantum and classical TD devices along the following lines: A) Linear versus nonlinear multimode transformations in TD devices: what are the principal distinctions between the two types of transformations? B) Classical versus quantum effects in NL TD devices: what are their main differences? Is quantumness an advantage or a disadvantage? C) Deterministic methods of achieving giant nonlinearity at the few-photon level via coherent processes, including multiatom-bath interactions which can paradoxically yield NL Hamiltonian effects: their comparison with probabilistic, measurement-based methods that can achieve similar NL effects in the quantum domain.