Testing identity of collections of quantum states: sample complexity analysis

03/26/2021

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by   Marco Fanizza, et al.

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We study the problem of testing identity of a collection of unknown quantum states given sample access to this collection, each state appearing with some known probability. We show that for a collection of d-dimensional quantum states of cardinality N, the sample complexity is O(√(N)d/ϵ^2), which is optimal up to a constant. The test is obtained by estimating the mean squared Hilbert-Schmidt distance between the states, thanks to a suitable generalization of the estimator of the Hilbert-Schmidt distance between two unknown states by Bădescu, O'Donnell, and Wright (https://dl.acm.org/doi/10.1145/3313276.3316344).