Continuous variable entanglement enhancement and manipulation by a sub-threshold type-II optical parametric amplifier

TL;DR

This paper demonstrates experimentally that quantum entanglement between optical modes can be enhanced and manipulated using a second non-degenerate optical parametric amplifier, with results aligning well with theoretical predictions.

Contribution

It introduces a method to enhance and control entanglement phase-sensitively using cascaded NOPAs, advancing quantum optics manipulation techniques.

Findings

Entanglement is increased at the second NOPA's cavity resonance.

Spectral features of correlation variances are significantly altered.

Experimental results agree with theoretical models.

Abstract

We experimentally demonstrate that the quantum entanglement between amplitude and phase quadratures of optical modes produced from a non-degenerate optical parametric amplifier (NOPA) can be enhanced and manipulated phase-sensitively by means of another NOPA. When both NOPAs operate at de-amplification, the entanglement degree is increased at the cavity resonance of the second NOPA. When the first NOPA operates at de-amplification and the second one at amplification, the spectral features of the correlation variances are significantly changed. The experimental results are in good agreement with the theoretical expectation.