Clifford group restricted eavesdroppers in quantum key distribution

Understand

Quantum key distribution (QKD) promises provably secure cryptography, even to attacks from an all-powerful adversary.

• However, with quantum computing development lagging behind QKD, the assumption that there exists an adversary equipped with a universal fault-tolerant quantum computer is unrealistic for at least the near future.
• Here, we explore the effect of restricting the eavesdropper's computational capabilities on the security of QKD, and find that improved secret key rates are possible.
• Specifically, we show that for a large class of discrete variable protocols higher key rates are possible if the eavesdropper is restricted to a unitary operation from the Clifford group.