Massively-multiplexed generation of Bell-type entanglement using a quantum memory

TL;DR

This paper demonstrates a scalable quantum entanglement generation method using a multiplexed atomic quantum memory, achieving over 500 modes and a 45 microsecond storage time, advancing quantum network technology.

Contribution

It introduces a massively multiplexed approach to generate bipartite entanglement with a programmable delay using a wavevector multiplexed quantum memory.

Findings

Generated entanglement across more than 500 modes.

Achieved Bell inequality violation over 3 standard deviations.

Maintained entanglement for at least 45 microseconds.

Abstract

High-rate generation of hybrid photon-matter entanglement remains a fundamental building block of quantum network architectures enabling protocols such as quantum secure communication or quantum distributed computing. While a tremendous effort has been made to overcome technological constraints limiting the efficiency and coherence times of current systems, an important complementary approach is to employ parallel and multiplexed architectures. Here we follow this approach experimentally demonstrating the generation of bipartite polarization-entangled photonic states across more than 500 modes, with a programmable delay for the second photon enabled by qubit storage in a wavevector multiplexed cold-atomic quantum memory. We demonstrate Clauser, Horne, Shimony, Holt inequality violation by over 3 standard deviations, lasting for at least 45 {\mu}s storage time for half of the modes. The ability to shape hybrid entanglement between the polarization and wavevector degrees of freedom provides not only multiplexing capabilities but also brings prospects for novel protocols.