Quantum receiver beyond the standard quantum limit of coherent optical communication

TL;DR

This paper demonstrates the first experimental quantum receiver that surpasses the standard quantum limit in coherent optical communication, enabling longer-distance quantum communication and advanced quantum information protocols.

Contribution

It presents an experimentally realized quantum receiver surpassing the SQL using a simple linear optics setup, a significant step forward in quantum communication technology.

Findings

Achieved over 90% detection efficiency.

Surpassed the standard quantum limit in coherent communication.

Enabled potential for longer-distance, amplification-free quantum channels.

Abstract

The most efficient modern optical communication is known as coherent communication and its standard quantum limit (SQL) is almost reachable with current technology. Though it has been predicted for a long time that this SQL could be overcome via quantum mechanically optimized receivers, such a performance has not been experimentally realized so far. Here we demonstrate the first unconditional evidence surpassing the SQL of coherent optical communication. We implement a quantum receiver with a simple linear optics configuration and achieve more than 90% of the total detection efficiency of the system. Such an efficient quantum receiver will provide a new way of extending the distance of amplification-free channels, as well as of realizing quantum information protocols based on coherent states and the loophole-free test of quantum mechanics.