Exponentially Enhanced non-Hermitian Cooling

TL;DR

This paper introduces a novel non-Hermitian cooling mechanism that leverages the exponential localization of wavefunctions at one edge of a system to achieve efficient thermal excitation reduction, applicable to various bosonic modes.

Contribution

It proposes a fundamentally different cooling method based on non-Hermiticity, redistributing thermal excitations rather than amplifying them, and does not depend on exceptional points or topology.

Findings

Cooling effect exponentially enhanced by auxiliary modes

Applicable to photons, phonons, magnons, etc.

Does not rely on exceptional points or topology

Abstract

Certain non-Hermitian systems exhibit the skin effect, whereby the wavefunctions become exponentially localized at one edge of the system. Such exponential amplification of wavefunction has received significant attention due to its potential applications in e.g., classical and quantum sensing. However, the opposite edge of the system, featured by the exponentially suppressed wavefunctions, remains largely unexplored. Leveraging this phenomenon, we introduce a non-Hermitian cooling mechanism, which is fundamentally distinct from traditional refrigeration or laser cooling techniques. Notably, non-Hermiticity will not amplify thermal excitations, but rather redistribute them. Hence, thermal excitations can be cooled down at one edge of the system, and the cooling effect can be exponentially enhanced by the number of auxiliary modes, albeit with a lower bound that depends on the dissipative interaction with the environment. Non-Hermitian cooling does not rely on intricate properties such as exceptional points or non-trivial topology, and it can apply to a wide range of Bosonic modes such as photons, phonons, magnons, etc.