Transmitter-device-independent quantum key distribution

Abstract

Transmitter-side device dependence is a longstanding yet implicit problem in quantum key distribution (QKD), in contrast to the thoroughly addressed measurement-side case. Quantum steering, which intrinsically distinguishes the roles of sender and receiver in entanglement certification, offers a natural route to lifting trust assumptions on the transmitter. Existing one-sided device-independent (1sDI) protocols primarily exploit steering as a security resource, and provoke a signaling loophole in the transmitter-receiver architecture. Here we formalize transmitter-device-independence on the basis of faithful quantum steering and propose a transmitter-device-independent (TDI) QKD protocol within 1sDI framework that closes this loophole through introducing a photon storage, thereby eliminating transmitter-side device vulnerabilities. In a proof-of-principle experiment we validate the feasibility of the TDI protocol, achieving a key-rate in the asymptotic limit of 410~bps over 27~km spool fiber. By delivering TDI security while retaining strong loss tolerance, our approach helps bridge the gap between security and practicality for real-world QKD deployments.

14 pages, 9 figures. Comments are welcome!