RLE Recent Papers

Quantum-Locked Key Distribution at Nearly the Classical Capacity Rate (Physical Review Letters)

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Cosmo Lupo and Seth Lloyd

DOI: http://dx.doi.org/10.1103/PhysRevLett.113.160502

Abstract:
Quantum data locking is a protocol that allows for a small secret key to (un)lock an exponentially larger amount of information, hence yielding the strongest violation of the classical one-time pad encryption in the quantum setting. This violation mirrors a large gap existing between two security criteria for quantum cryptography quantified by two entropic quantities: the Holevo information and the accessible information. We show that the latter becomes a sensible security criterion if an upper bound on the coherence time of the eavesdropper’s quantum memory is known. Under this condition, we introduce a protocol for secret key generation through a memoryless qudit channel. For channels with enough symmetry, such as the d-dimensional erasure and depolarizing channels, this protocol allows secret key generation at an asymptotic rate as high as the classical capacity minus one bit.

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Quantum-Locked Key Distribution at Nearly the Classical Capacity Rate (Physical Review Letters)

Professor Seth Lloyd