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arXiv · 1903.12533

Semi-device-independent self-testing of unsharp measurements

Nikolai Miklin·Jakub J. Borkała·Marcin Pawłowski
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Abstract

Unsharp quantum measurements provide a resource in scenarios where one faces the trade-off between information gain and disturbance. In this work we introduce a prepare-transform-measure scenario in which two-outcome unsharp measurements outperform their sharp counterparts, as well as any stochastic strategy involving dichotomic projective measurements. Based on that, we propose a scheme for semi-device-independent self-testing of unsharp measurements and show that all two-outcome qubit measurements can be characterized in a robust way. Along with the main result, in this work we introduce a method, based on semidefinite programming, for bounding quantum correlations in scenarios with sequential measurements of length two. This method can also be applied to refine security analysis of the semi-device-independent one-way quantum key distribution. We also present new information gain-disturbance relation for pairs of dichotomic measurements.

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Nikolai Miklin, Jakub J. Borkała, Marcin Pawłowski. 2019-03-29. Semi-device-independent self-testing of unsharp measurements. https://doi.org/10.1103/physrevresearch.2.033014

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