Secret-key distillation across a quantum wiretap channel under restricted eavesdropping

Ziwen Pan, Kaushik P. Seshadreesan, William Clark, Mark R. Adcock, Ivan B. Djordjevic, Jeffrey H. Shapiro, Saikat Guha

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The theory of quantum cryptography aims to guarantee unconditional information-theoretic security against an omnipotent eavesdropper. In many practical scenarios, however, the assumption of an all-powerful adversary is excessive and can be relaxed considerably. In this paper we study secret-key distillation across a lossy and noisy quantum wiretap channel between Alice and Bob, with a separately parameterized realistically lossy quantum channel to the eavesdropper Eve. We show that under such restricted eavesdropping, the key rates achievable can exceed the secret-key-distillation capacity against an unrestricted eavesdropper in the quantum wiretap channel. Furthermore, we show upper bounds on the key rates based on the relative entropy of entanglement. This simple restricted eavesdropping model is widely applicable, for example, to free-space quantum optical communication, where realistic collection of light by Eve is limited by the finite size of her optical aperture. Future work will include calculating bounds on the amount of light Eve can collect under various realistic scenarios.

Original languageEnglish (US)
Article number024044
JournalPhysical Review Applied
Issue number2
StatePublished - Aug 2020

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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