Phase Locking between Two All-Optical Quantum Memories

TL;DR

This paper demonstrates phase locking of two all-optical quantum memories, enabling controlled release of entangled single-photon states with preserved entanglement and nonclassicality over significant time differences.

Contribution

It introduces an experimental method for phase locking two quantum memories with independent release times, advancing multi-mode quantum state control.

Findings

Entanglement preserved up to 400 ns delay

Nonclassicality confirmed by Wigner negativity

Independent control of release times for each mode

Abstract

Optical approaches to quantum computation require the creation of multi-mode photonic quantum states in a controlled fashion. Here we experimentally demonstrate phase locking of two all-optical quantum memories, based on a concatenated cavity system with phase reference beams, for the time-controlled release of two-mode entangled single-photon states. The release time for each mode can be independently determined. The generated states are characterized by two-mode optical homodyne tomography. Entanglement and nonclassicality are preserved for release-time differences up to 400 ns, confirmed by logarithmic negativities and Wigner-function negativities, respectively.