Quantum entanglement

Physics

Proof of concept

Cryptography

Key (lock)

Postselection

Operating system

Algorithm

Quantum cryptography

Key generation

Quantum information

Computer science

Quantum mechanics

Quantum key distribution

Computer security

Quantum

Physical Review Letters

The twin-field (TF) quantum key distribution (QKD) protocol and its variants are highly attractive because they can beat the well-known fundamental limit of the secret key rate for point-to-point QKD without quantum repeaters (repeaterless bound). In this Letter, we perform a proof-of-principle experimental demonstration of TFQKD based on the protocol proposed by Curty, Azuma, and Lo, which removes the need for postselection on the matching of a global phase from the original TFQKD scheme and can deliver a high secret key rate. Furthermore, we employ a Sagnac loop structure to help overcome the major difficulty in the practical implementation of TFQKD, namely, the need to stabilize the phase of the quantum state over kilometers of fiber. As a proof-of-principle demonstration, the estimated secure key rate from our experimental TFQKD data at the high loss region surpasses the repeaterless bound of QKD with current technology.

Proof-of-Principle Experimental Demonstration of Twin-Field Type Quantum Key Distribution