Bell Test Over Extremely High-Loss Channels: Towards Distributing Entangled Photon Pairs Between Earth and Moon

TL;DR

This paper proposes a method to distribute entangled photons between Earth and Moon over extremely high-loss channels, demonstrating Bell test feasibility with human-generated random settings and high photon generation rates.

Contribution

It introduces a high-rate entangled photon source and a Bell test over a 1.28-light-second distance with simulated 103 dB loss, advancing long-distance quantum entanglement experiments.

Findings

Bell test performed over simulated 103 dB loss

Entangled photon source with 1 GHz rate developed

Violation of Bell's inequality observed

Abstract

Quantum entanglement was termed "spooky action at a distance" in the well-known paper by Einstein, Podolsky, and Rosen. Entanglement is expected to be distributed over longer and longer distances in both practical applications and fundamental research into the principles of nature. Here, we present a proposal for distributing entangled photon pairs between the Earth and Moon using a Lagrangian point at a distance of 1.28 light seconds. One of the most fascinating features in this long-distance distribution of entanglement is that we can perform Bell test with human supply the random measurement settings and record the results while still maintaining space-like intervals. To realize a proof-of-principle experiment, we develop an entangled photon source with 1 GHz generation rate, about 2 orders of magnitude higher than previous results. Violation of the Bell's inequality was observed under a total simulated loss of 103 dB with measurement settings chosen by two experimenters. This demonstrates the feasibility of such long-distance Bell test over extremely high-loss channels, paving the way for the ultimate test of the foundations of quantum mechanics.