Measurement-device-independent quantum key distribution with insecure sources

Area of Science:

• Quantum Information Science
• Quantum Cryptography
• Quantum Communication Security

Background:

• Measurement-device-independent quantum key distribution (MDI-QKD) eliminates detection side-channel vulnerabilities.
• Practical MDI-QKD implementations remain susceptible to imperfections and side channels in quantum sources.

Purpose of the Study:

• To develop a security proof for MDI-QKD that accounts for potential source imperfections and side channels.
• To investigate the impact of these imperfections on the performance of single-photon sources in MDI-QKD.

Main Methods:

• Integration of a novel reference technique with MDI-QKD formalism.
• Utilization of reference states and an upper bound on source quality parameters.
• Analysis of asymptotic performance for single-photon sources.

Main Results:

• The proposed formalism successfully proves MDI-QKD security against source imperfections.
• Side channels associated with quantum sources were shown to significantly degrade key rates.
• The impact of uncharacterized source side channels on MDI-QKD performance was quantified.

Conclusions:

• A robust security framework for MDI-QKD against source imperfections is established.
• Minimizing or characterizing source side channels is crucial for achieving high key rates in MDI-QKD.
• The developed technique provides a more realistic assessment of MDI-QKD security in practical scenarios.