Measurement-Device-Independent Verification of a Quantum Memory

TL;DR

This paper demonstrates a measurement-device-independent method to verify an atomic-ensemble quantum memory by storing, retrieving, and entangling photons, ensuring the memory preserves quantum entanglement over time.

Contribution

It introduces a novel verification scheme for quantum memories that does not depend on measurement device trustworthiness, using Bell-state measurements and quantum random inputs.

Findings

Successfully stored and retrieved photons with preserved entanglement.

Verified the quantum memory's ability to maintain entanglement over long durations.

Implemented a measurement-device-independent verification protocol.

Abstract

In this paper we report an experiment that verifies an atomic-ensemble quantum memory via a measurement-device-independent scheme. A single photon generated via Rydberg blockade in one atomic ensemble is stored in another atomic ensemble via electromagnetically induced transparency. After storage for a long duration, this photon is retrieved and interfered with a second photon to perform joint Bell-state measurement (BSM). Quantum state for each photon is chosen based on a quantum random number generator respectively in each run. By evaluating correlations between the random states and BSM results, we certify that our memory is genuinely entanglement-preserving.