Breaking reciprocity by designed loss

TL;DR

This paper demonstrates how specifically designed loss mechanisms in open quantum systems can break reciprocity, enabling unidirectional and non-reciprocal state propagation through linear and nonlinear schemes, with potential applications in optical devices.

Contribution

It introduces novel methods to achieve non-reciprocal propagation in quantum systems using designed loss, including unidirectional states, optical insulators, and circulators.

Findings

Unidirectional propagation for certain symmetric states in linear schemes.

Single-mode optical insulator using nonlinear designed losses.

Non-reciprocal circulator with dissipatively coupled waveguides.

Abstract

In this paper we show how designed loss in open quantum systems can break reciprocity of the state propagation, and how the non-reciprocal and even unidirectional propagation can be achieved for different kinds of designed loss, both linear and nonlinear ones. In particular, we show how a unidirectional propagation can be achieved for states of certain symmetry in linear schemes, demonstrate possibility of building a single-mode optical insulator by combining two kinds of nonlinear designed losses, and the way to build non-reciprocal circulator with a planar structure of dissipatively coupled waveguides. We discuss feasibility of the considered schemes and suggest possible realizations.