Bright continuous-variable entanglement from the quantum optical dimer

TL;DR

This paper theoretically demonstrates that a system of two coupled second harmonic generators inside a cavity can produce tunable, macroscopic entangled light with controllable properties, without requiring a threshold for oscillation.

Contribution

It introduces a novel system using coupled second harmonic generators for generating macroscopic entanglement with tunable features, unlike traditional downconverter systems.

Findings

System produces quadrature squeezed light and EPR correlations.

Entanglement is tunable via pump, coupling, and detuning.

No oscillation threshold needed for macroscopic occupation.

Abstract

We show theoretically that two evanescently coupled $\chi^{(2)}$ second harmonic generators inside a Fabry-Perot cavity provide a tunable source of quadrature squeezed light, Einstein-Podolsky-Rosen correlations and quantum entanglement. Unlike systems using coupled downconverters, second harmonic generation has no oscillation threshhold, so that the entangled fields become macroscopically occupied as soon as the pumping fields are turned on. This system also gives two frequencies at which the entangled fields can have macroscopic intensity. We show how the entanglement properties can be controlled by adjusting the pumping, the coupling strengths and the cavity detunings.