Nonreciprocity in Photon Pair Correlations

TL;DR

This paper demonstrates a novel form of nonreciprocity in photon pair correlations, where reversing pump direction significantly affects coherence functions without changing linear transmission, with experimental and theoretical validation.

Contribution

It introduces and verifies a new type of nonreciprocity in photon pair correlations, distinct from linear transmission effects, using silicon microdisk experiments.

Findings

Reversal of pump direction causes substantial extinction of coherence functions.

Nonreciprocity appears in second-order coherence functions, not in linear transmission.

Experimental results match theoretical predictions.

Abstract

Nonreciprocal optical systems have found many applications altering the linear transmission of light as a function of its propagation direction. Here we consider a new class of nonreciprocity which appears in photon pair correlations and not in linear transmission. We experimentally demonstrate and theoretically verify this nonreciprocity in the second-order coherence functions of photon pairs produced by spontaneous four-wave mixing in a silicon microdisk. Reversal of the pump propagation direction can result in substantial extinction of the coherence functions without altering pump transmission.