Differential-quadrature-phase-shift quantum digital signature

Area of Science:

• Quantum Information Science
• Cryptography
• Optical Communication

Background:

• Conventional quantum digital signature (QDS) protocols often require complex post-processing and secure channels for information exchange.
• Existing QDS schemes can be computationally intensive and resource-demanding for key creation and verification.

Purpose of the Study:

• To introduce a novel, simplified quantum digital signature (QDS) scheme named "differential quadrature phase-shift QDS."
• To eliminate the need for post-processing and secured/authenticated channels in QDS protocols.
• To enhance the efficiency and accessibility of quantum key distribution.

Main Methods:

• A message sender broadcasts a weak coherent pulse train with four distinct phases: {0, π/2, π, 3π/2}.
• Recipients independently generate their authentication keys directly from the broadcasted signal.
• Security analysis is performed using binomial distributions, differing from conventional Hoeffding's inequality methods.

Main Results:

• The proposed differential quadrature phase-shift QDS scheme obviates the necessity for information exchange between sender and recipients post-transmission.
• Key creation is simplified, removing the requirement for secured or authenticated channels.
• The scheme demonstrates robust security properties analyzed via binomial distributions.

Conclusions:

• The differential quadrature phase-shift QDS offers a more accessible and efficient alternative to conventional QDS protocols.
• This novel scheme significantly reduces the complexity and infrastructure requirements for secure quantum communication.
• The findings pave the way for broader adoption of quantum-secure digital signatures.