Bipartite entanglement extracted from multimode squeezed light generated in lossy waveguides

TL;DR

This paper investigates how bipartite entanglement can be extracted from multimode squeezed light generated in lossy waveguides, demonstrating the role of squeezing and optimal measurement modes for quantum information applications.

Contribution

It introduces a method to quantify and maximize bipartite entanglement from multimode Gaussian states in lossy waveguides, with a comparison of measurement bases.

Findings

Squeezing quantifies entanglement in the studied states.

Optimal measurement basis maximizes bipartite entanglement.

Comparison of measurement bases shows advantages of the constructed basis.

Abstract

Entangled two-mode Gaussian states constitute an important building block for continuous variable quantum computing and communication protocols. In this work, we theoretically study two-mode bipartite states which are extracted from multimode light generated via type-II parametric down-conversion (PDC) in lossy waveguides. For these states, we demonstrate that the squeezing quantifies entanglement and we construct a measurement basis which results in the maximal bipartite entanglement. We illustrate our findings by numerically solving the spatial master equation for PDC in a Markovian environment. The optimal measurement modes are compared with two widely-used broadband bases: the Mercer-Wolf basis (the first-order coherence basis) and the Williamson-Euler basis.