Finite-key bound for semi-device-independent quantum key distribution

Area of Science:

• Quantum Information Science
• Quantum Cryptography
• Quantum Communication

Background:

• Device-Independent (DI) Quantum Key Distribution (QKD) offers high security but is experimentally challenging due to its reliance on Bell inequality violations.
• Semi-Device-Independent (SDI) QKD simplifies implementation by confining quantum states to finite-dimensional Hilbert spaces, making it more practical with current technology.

Purpose of the Study:

• To propose a practical prepare-and-measure protocol for Semi-Device-Independent (SDI) Quantum Key Distribution (QKD).
• To establish a security bound for this protocol under realistic conditions with finite resources.
• To investigate the impact of the finite-key effect on the security of SDI QKD.

Main Methods:

• Development of a practical prepare-and-measure SDI QKD protocol based on the BB84 scheme.
• Introduction of min-entropy for rigorous security proof.
• Numerical simulations to analyze the finite-key effect under practical constraints.

Main Results:

• A feasible SDI QKD protocol is proposed, leveraging existing experimental capabilities.
• A security bound is derived using min-entropy, accounting for finite resources.
• Simulations indicate that the finite-key effect significantly influences security and cannot be disregarded in upcoming experiments.

Conclusions:

• The proposed SDI QKD protocol offers a practical approach to secure key distribution.
• The security analysis provides a realistic bound, emphasizing the need to consider finite resources.
• The finite-key effect is a critical factor for the successful implementation of future SDI QKD systems.