Photon pair generation in a lossy microring resonator. II. Entanglement in the output mixed Gaussian squeezed state

TL;DR

This paper investigates how coupling and propagation losses in a microring resonator affect the entanglement of the generated signal-idler squeezed vacuum state, using log-negativity as a measure.

Contribution

It introduces a detailed analysis of entanglement in a lossy microring resonator considering both classical and quantum noise effects, advancing understanding of quantum state generation in realistic devices.

Findings

Entanglement depends critically on coupling and loss parameters.

Quantum Langevin noise influences the entanglement structure.

Loss mechanisms can diminish or modify the output entanglement.

Abstract

In this work we examine the entanglement of the output signal-idler squeezed vacuum state in the Heisenberg picture as a function of the coupling and internal propagation loss parameters of a microring resonator. Using the log-negativity as a measure of entanglement for a mixed Gaussian state, we examine the competitive effects of the transfer matrix that encodes the classical phenomenological loss, as well as the matrix that that incorporates the coupling and internal propagation loss due to the quantum Langevin noise fields required to preserve unitarity of the composite system,(signal-idler) and environment (noise) structure.