Twin-Field Quantum Digital Signature with Fully Discrete Phase Randomization.

Area of Science:

• Quantum Information Science
• Quantum Cryptography
• Quantum Communication

Background:

• Current quantum digital signature (QDS) protocols face limitations in signature rate and secure transmission distance due to the fundamental rate-loss bound.
• Existing QDS protocols like BB84-QDS and measurement-device-independent QDS (MDI-QDS) require further improvements for practical applications.

Purpose of the Study:

• To propose and investigate a novel twin-field quantum digital signature (TF-QDS) protocol.
• To enhance the performance of QDS in terms of signature rate and secure transmission distance.
• To assess the feasibility of experimental implementation for practical QDS systems.

Main Methods:

• Development of a TF-QDS protocol featuring fully discrete phase randomization.
• Performance investigation under a two-intensity decoy-state setting.
• Optimization of signal and decoy state intensities for different distances.
• Numerical simulations to compare TF-QDS with existing QDS protocols (BB84-QDS, MDI-QDS).

Main Results:

• The proposed TF-QDS protocol, using as few as six discrete random phases, demonstrates a higher signature rate and longer secure transmission distance compared to BB84-QDS and MDI-QDS.
• Numerical simulations confirm superior performance of the proposed TF-QDS over other twin-field key generation protocols (TF-KGPs).
• The TF-QDS protocol shows feasibility for experimental implementation with current quantum communication devices.

Conclusions:

• The TF-QDS protocol offers significant advantages in signature rate and secure transmission distance, primarily due to single-photon interference and precise discrete phase matching.
• The protocol overcomes the limitations of current QDS, paving the way for more robust and secure quantum communication.
• The demonstrated experimental feasibility makes the TF-QDS protocol a promising candidate for practical quantum digital signature systems.