High-Performance Fully Passive Discrete-State Continuous-Variable Quantum Key Distribution with Local Local...

Area of Science:

• Quantum Information Science
• Quantum Cryptography
• Optical Communication Systems

Background:

• Continuous-variable quantum key distribution (CV-QKD) systems typically rely on active optical modulators, introducing potential security vulnerabilities.
• Eliminating modulator side channels is crucial for enhancing the practical security of QKD protocols.
• Existing CV-QKD architectures can be complex, necessitating simplification for wider adoption.

Purpose of the Study:

• To propose and demonstrate a fully passive discrete-state continuous-variable quantum key distribution (CV-QKD) protocol.
• To enhance security by eliminating modulator side channels through the use of a local local oscillator.
• To achieve high performance and practical security in CV-QKD systems.

Main Methods:

• Implementation of a fully passive CV-QKD system.
• Utilizing a local local oscillator to mitigate source-side side channels.
• Employing specially designed phase rotation and discretization techniques.

Main Results:

• Achieved a maximum fiber transmission distance of 100 km at a 1 GHz repetition rate with a secret key rate of 70.7 kbps under asymptotic security.
• Distributed secret keys at 25 km fiber with a rate of 1.66 Mbps in composable security.
• Demonstrated a simplified CV-QKD architecture, eliminating the need for optical modulators and random number generators.

Conclusions:

• The proposed passive CV-QKD protocol offers robust practical security and superior performance comparable to active systems.
• This protocol significantly simplifies CV-QKD system architecture.
• The technology is well-suited for quantum metropolitan area networks and quantum access networks demanding high realistic security.