Observation of Quantum Fingerprinting Beating the Classical Limit

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 transmitted information 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 a proof-of-principle experimental demonstration of a quantum fingerprinting protocol that for the first time surpasses the ultimate classical limit to transmitted information. Ultralow noise superconducting single-photon detectors and a stable fiber-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 fiber for input sizes of up to 2 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.
National Fundamental Research Program of China (Grants No. 2011CB921300 and No. 2013CB3368000
National Natural Science Foundation (China)
Chinese Academy of Sciences
10000-Plan of Shandong Province
Management Committee of Shanghai Zhangjiang High-Technology Industrial Development Zone
United States. Office of Naval Research
United States. Air Force Office of Scientific Research