Coherent spin-wave processor of stored optical pulses

TL;DR

This paper demonstrates a multi-dimensional spin-wave quantum memory capable of storing, manipulating, and retrieving optical pulses with high fidelity, advancing optical quantum information processing and communication.

Contribution

It introduces a novel multimode quantum memory that performs complex operations and on-demand retrieval, combining storage, interference, and processing of optical pulses.

Findings

Achieved 95% interference visibility between spin-wave modes.

Demonstrated complex beamsplitter operations during storage.

Realized on-demand retrieval through phase-matching engineering.

Abstract

A device being a pinnacle of development of an optical quantum memory should combine the capabilities of storage, inter-communication and processing of stored information. In particular, the ability to capture a train of optical pulses, interfere them in an arbitrary way and finally perform on-demand release would in a loose sense realize an optical analogue of a Turing Machine. Here we demonstrate the operation of an optical quantum memory being able to store optical pulses in the form of collective spin-wave excitations in a multi-dimensional wavevector space. During storage, we perform complex beamsplitter operations and demonstrate a variety of protocol implemented as the processing stage, including interfering a pair of spin-wave modes with 95\% visibility. By engineering the phase-matching at the readout stage we realize the on-demand retrieval. The highly multimode structure of the presented quantum memory lends itself both to enhancing classical optical telecommunication as well as parallel processing of optical qubits at the single-photon level.