Non-reciprocal quantum interactions and devices via autonomous feed-forward

TL;DR

This paper presents a framework for creating non-reciprocal quantum devices using autonomous feed-forward, extending reservoir engineering techniques to develop quantum amplifiers that are non-reciprocal, quantum-limited, and free from gain-bandwidth constraints.

Contribution

It introduces an autonomous feed-forward perspective to reservoir-engineered non-reciprocal quantum interactions and demonstrates a non-reciprocal, quantum-limited amplifier without gain-bandwidth limitations.

Findings

Developed a method to realize non-reciprocal quantum interactions via autonomous feed-forward.

Constructed a phase-preserving cavity amplifier that is non-reciprocal and quantum-limited.

Achieved an amplifier free of fundamental gain-bandwidth constraints.

Abstract

In a recent work [A. Metelmann and A. A. Clerk, Phys. Rev. X 5, 021025 (2015)], a general reservoir-engineering approach for generating non-reciprocal quantum interactions and devices was described. We show here how in many cases this general recipe can be viewed as an example of autonomous feed-forward: the full dissipative evolution is identical to the unconditional evolution in a setup where an observer performs an ideal quantum measurement of one system, and then uses the results to drive a second system. We also extend the application of this approach to non-reciprocal quantum amplifiers, showing the added functionality possible when using two engineered reservoirs. In particular, we demonstrate how to construct an ideal phase-preserving cavity-based amplifier which is full non-reciprocal, quantum-limited and free of any fundamental gain-bandwidth constraint.