Phase control of a longitudinal momentum entangled photon state by a deformable membrane mirror

TL;DR

This paper demonstrates how a deformable membrane mirror can be used for real-time phase control of a two-photon momentum-entangled state, stabilizing quantum interference despite phase fluctuations.

Contribution

It introduces a feedback control method using a deformable mirror to stabilize the phase of entangled photons in an interferometric setup.

Findings

Achieved stabilization of coincidence rate within 1.5 standard deviations of Poisson noise.

Demonstrated phase stabilization over 2000 seconds.

Validated the use of deformable mirrors for quantum state phase control.

Abstract

We propose a paradigmatic demonstration of the potentialities of a deformable mirror for closed-loop control of a two-photon momentum-entangled state, subject to phase fluctuations. A custom-made membrane mirror is used to set a relative phase shift between the arms of an interferometric apparatus. The control algorithm estimates the phase of the quantum state, by measurements of the coincidence events at the output ports of the interferometer, and uses the measurements results to provide a feedback signal to the deformable mirror. Stabilization of the coincidence rate to within 1.5 standard deviation of the Poissonian noise is demonstrated over 2000 seconds.