Quantum cryptography without detector vulnerabilities using optically-seeded lasers

TL;DR

This paper presents a new laser seeding technique enabling high-rate, detector-vulnerability-free quantum cryptography, significantly advancing the practicality and security of quantum communication systems.

Contribution

Introduction of a pulsed laser seeding method that achieves high-visibility interference in quantum cryptography without detector vulnerabilities, reaching over 1 Mb/s.

Findings

Achieved quantum cryptography at over 1 Megabit per second.

Demonstrated a 2 to 6 orders of magnitude improvement in key rates.

Enabled practical, detection-vulnerability-free quantum secure communication.

Abstract

Security in quantum cryptography is continuously challenged by inventive attacks targeting the real components of a cryptographic setup, and duly restored by new counter-measures to foil them. Due to their high sensitivity and complex design, detectors are the most frequently attacked components. Recently it was shown that two-photon interference from independent light sources can be exploited to avoid the use of detectors at the two ends of the communication channel. This new form of detection-safe quantum cryptography, called Measurement-Device-Independent Quantum Key Distribution (MDI-QKD), has been experimentally demonstrated, but with modest delivered key rates. Here we introduce a novel pulsed laser seeding technique to obtain high-visibility interference from gain-switched lasers and thereby perform quantum cryptography without detector vulnerabilities with unprecedented bit rates, in excess of 1 Mb/s. This represents a 2 to 6 orders of magnitude improvement over existing implementations and for the first time promotes the new scheme as a practical resource for quantum secure communications.