# Manipulating the flow of thermal noise in quantum devices

## TL;DR

This paper proposes a theoretical framework for controlling the unidirectional flow of thermal noise in quantum systems, enabling the development of thermal rectifiers and related devices for quantum technology applications.

## Contribution

It introduces a novel method to manipulate thermal noise flow in quantum cascaded systems, expanding control beyond signal routing to thermal management.

## Key findings

- Unidirectional thermal noise flow is theoretically achievable in quantum cascaded systems.
- Mechanical resonators can be engineered to act as artificial reservoirs for thermal noise control.
- The approach enables potential devices like thermal rectifiers, modulators, and routers.

## Abstract

There has been significant interest recently in using complex quantum systems to create effective nonreciprocal dynamics. Proposals have been put forward for the realization of artificial magnetic fields for photons and phonons; experimental progress is fast making these proposals a reality. Much work has concentrated on the use of such systems for controlling the flow of signals, e.g., to create isolators or directional amplifiers for optical signals. In this paper, we build on this work but move in a different direction. We develop the theory of and discuss a potential realization for the controllable flow of thermal noise in quantum systems. We demonstrate theoretically that the unidirectional flow of thermal noise is possible within quantum cascaded systems. Viewing an optomechanical platform as a cascaded system we here that one can ultimately control the direction of the flow of thermal noise. By appropriately engineering the mechanical resonator, which acts as an artificial reservoir, the flow of thermal noise can be constrained to a desired direction, yielding a thermal rectifier. The proposed quantum thermal noise rectifier could potentially be used to develop devices such as a thermal modulator, a thermal router, and a thermal amplifier for nanoelectronic devices and superconducting circuits.