Making Existing Quantum Position Verification Protocols Secure Against Arbitrary Transmission Loss

Area of Science:

• Quantum cryptography
• Quantum information science
• Secure communication protocols

Background:

• Signal loss in quantum cryptography compromises security, particularly in quantum position verification (QPV).
• Existing QPV protocols are vulnerable to even minor transmission losses between verifiers and the prover.
• High transmission loss limits the practical distance and security of quantum cryptographic systems.

Purpose of the Study:

• To develop a modified quantum position verification protocol resilient to high transmission loss.
• To ensure that signal loss does not compromise the security of QPV protocols.
• To enhance the feasibility and security guarantees of QPV over longer distances.

Main Methods:

• Modification of traditional QPV protocols.
• Implementation of photon presence detection and a small time delay.
• Inclusion of a commitment step before protocol execution.
• Adaptation of protocols based on BB84 states (QPV_{BB84}^{f}).

Main Results:

• Reduced the relevant loss rate to only that of the prover's laboratory.
• Achieved essentially the same security guarantees as the original QPV protocol.
• Demonstrated the irrelevance of high transmission loss for a class of QPV protocols.
• Developed the adapted protocol c-QPV_{BB84}^{f}.

Conclusions:

• The adapted c-QPV_{BB84}^{f} protocol offers strong security guarantees against signal loss.
• The modified protocol enhances the feasibility of QPV for longer communication distances.
• Practical implementation and parameter estimates for the protocol are discussed.