Beware of Greeks bearing entanglement? Quantum covert channels, information flow and non-local games

• URL: http://arxiv.org/abs/2202.02069v1
• Date: Fri, 4 Feb 2022 10:49:20 GMT
• Title: Beware of Greeks bearing entanglement? Quantum covert channels, information flow and non-local games
• Authors: David Mestel
• Abstract summary: We show that quantum entanglement can in fact increase the capacity of a classical covert channel, in the presence of an active adversary. A zero-capacity channel is not improved by entanglement, so entanglement cannot create purely quantum' covert channels.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Can quantum entanglement increase the capacity of (classical) covert channels? To one familiar with Holevo's Theorem it is tempting to think that the answer is obviously no. However, in this work we show: quantum entanglement can in fact increase the capacity of a classical covert channel, in the presence of an active adversary; on the other hand, a zero-capacity channel is not improved by entanglement, so entanglement cannot create `purely quantum' covert channels; the problem of determining the capacity of a given channel in the presence of entanglement is undecidable; but there is an algorithm to bound the entangled capacity of a channel from above, adapted from the semi-definite hierarchy from the theory of non-local games, whose close connection to channel capacity is at the core of all of our results.

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