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Pretty simple bounds on quantum state discrimination

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arxiv 1908.08312 v2 pith:W6IB6JRT submitted 2019-08-22 quant-ph

Pretty simple bounds on quantum state discrimination

classification quant-ph
keywords statequantummeasurementunknowncopiesdiscriminationprettystates
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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We show that the quantum measurement known as the pretty good measurement can be used to identify an unknown quantum state picked from any set of $n$ mixed states that have pairwise fidelities upper-bounded by a constant below 1, given $O(\log n)$ copies of the unknown state, with high success probability in the worst case. If the unknown state is promised to be pure, there is an explicit measurement strategy which solves this worst-case quantum state discrimination problem with $\widetilde{O}(\|G\|)$ copies, where $G$ is the Gram matrix of the states.

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Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Contextual advantage implies limited distinguishability in any physical theory

    quant-ph 2026-07 accept novelty 6.0

    In any generalized probabilistic theory, any state set that powers a contextuality-based advantage must obey strict upper bounds on how often its states can be correctly distinguished.