Experimental composable key distribution using discrete-modulated continuous variable quantum cryptography

Area of Science:

• Quantum Information Science
• Quantum Cryptography
• Telecommunications Technology

Background:

• Secure data communication relies on secure key exchange over public channels.
• Quantum Key Distribution (QKD) offers information-theoretic security using quantum physics principles.
• Discrete Modulated (DM) Continuous Variable (CV) QKD is promising for scalable quantum-safe communication due to its simplicity and compatibility with existing infrastructure.

Purpose of the Study:

• To experimentally demonstrate a four-state DM CVQKD system.
• To generate composable finite-size keys secure against collective attacks.
• To assess the feasibility of large-scale deployment using standard telecommunication components.

Main Methods:

• Experimental implementation of a four-state DM CVQKD system.
• Transmission of 2.3 × 10^9 coherent quantum states over a 20 km fiber channel.
• Application of an advanced security proof and meticulous parameter selection.

Main Results:

• Successful generation of composable finite-size keys.
• Achievement of a positive composable key rate of 11.04 × 10^-3 bits/symbol.
• Demonstration of secure key distribution over a 20 km fiber link.

Conclusions:

• The experimental demonstration represents a significant advancement in practical QKD.
• The system's performance highlights the potential for high-performance, cost-effective quantum key distribution networks.
• This work supports the large-scale deployment of quantum-safe communication using standard telecommunication technologies.