Observation of quantum fingerprinting beating the classical limit

TL;DR

This paper reports the first experimental demonstration of quantum fingerprinting surpassing the classical information transmission limit, using advanced photon detection and fiber optics over long distances, advancing quantum communication capabilities.

Contribution

The study experimentally demonstrates quantum fingerprinting exceeding classical limits in information transmission over 20 km fiber, a significant step in practical quantum communication.

Findings

Quantum fingerprinting beats classical information limits

Achieved transmission of less than classical lower bound over 20 km fiber

Operated with input sizes up to two Gbits

Abstract

Quantum communication has historically been at the forefront of advancements, from fundamental tests of quantum physics to utilizing the quantum-mechanical properties of physical systems for practical applications. In the field of communication complexity, quantum communication allows the advantage of an exponential reduction in the information transmitted over classical communication to accomplish distributed computational tasks. However, to date, demonstrating this advantage in a practical setting continues to be a central challenge. Here, we report an experimental demonstration of a quantum fingerprinting protocol that for the first time surpasses the ultimate classical limit to transmitted information. Ultra-low noise superconducting single-photon detectors and a stable fibre-based Sagnac interferometer are used to implement a quantum fingerprinting system that is capable of transmitting less information than the classical proven lower bound over 20 km standard telecom fibre for input sizes of up to two Gbits. The results pave the way for experimentally exploring the advanced features of quantum communication and open a new window of opportunity for research in communication complexity and testing the foundations of physics.