Coherent quantum dynamics of systems with coupling-induced creation pathways

TL;DR

This paper introduces a novel quantum interference phenomenon in optical microcavities that enables coherent control of entangled biphoton states, with potential for creating complex multi-photon quantum states.

Contribution

It demonstrates a new class of quantum interference effects involving coupling-induced creation pathways and coherent conversion in microcavities, allowing tunable entanglement.

Findings

Observation of cyclically evolving path-entanglement.

Control over the degree of entanglement via interference strength.

Potential for generating exotic multi-photon states.

Abstract

Many technologies emerging from quantum information science heavily rely upon the generation and manipulation of entangled quantum states. Here, we propose and demonstrate a new class of quantum interference phenomena that arise when states are created in and coherently converted between the propagating modes of an optical microcavity. The modal coupling introduces several new creation pathways to a nonlinear optical process within the device, which quantum mechanically interfere to drive the system between states in the time domain. The coherent conversion entangles the generated biphoton states between propagation pathways, leading to cyclically evolving path-entanglement and the manifestation of coherent oscillations in second-order temporal correlations. Furthermore, the rich device physics is harnessed to tune properties of the quantum states. In particular, we show that the strength of interference between pathways can be coherently controlled, allowing for manipulation of the degree of entanglement, which can even be entirely quenched. The states can likewise be made to flip-flop between exhibiting initially correlated or uncorrelated behavior. Based upon these observations, a proposal for extending beyond a single device to create exotic multi-photon states is also discussed.