Experimental generation of 6 dB continuous variable entanglement from a nondegenerate optical parametric amplifier

TL;DR

This paper reports an experimental enhancement of continuous variable entanglement from a nondegenerate optical parametric amplifier by technical improvements, achieving 6 dB of quantum correlations below the noise limit.

Contribution

The study introduces specific technical improvements that significantly increase entanglement levels in a NOPA system, reaching 6 dB below the quantum noise limit.

Findings

Entanglement improved from ~4 dB to ~6 dB below quantum noise limit.

Use of a mode cleaner and phase stabilization enhances quantum correlations.

Experimental validation of entanglement enhancement techniques.

Abstract

We experimentally demonstrated that the quantum correlations of amplitude and phase quadratures between signal and idler beams produced from a non-degenerate optical parametric amplifier (NOPA) can be significantly improved by using a mode cleaner in the pump field and reducing the phase fluctuations in phase locking systems. Based on the two technical improvements the quantum entanglement measured with a two-mode homodyne detector is enhanced from ~ 4 dB to ~ 6 dB below the quantum noise limit using the same NOPA and nonlinear crystal.