Operation fidelity explored by numerical range of Kraus operators

Abstract

Present-day quantum devices require precise implementation of desired quantum channels. To characterize the quality of implementation one uses the average operation fidelity $F$, defined as the fidelity between an initial pure state and its image with respect to the analyzed operation, averaged over an ensemble of pure states. We analyze statistical properties of the operation fidelity for low-dimensional channels and study its extreme values and probability distribution, both of which can be used for statistical channel discrimination. These results are obtained with help of the joint numerical range of the set of Kraus operators representing a channel. Analytic expressions for the density $P\left(F\right)$ are derived in some particular cases including unitary and mixed unitary channels as well as quantum maps represented by commuting Kraus operators. Measured distributions of operation fidelity can be used to distinguish between two quantum operations.

14 pages, 5 figures, updated section on probabilistic channel discrimination

References in corpus (8)

• Direct Fidelity Estimation from Few Pauli Measurements
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Cited by in corpus (2)

• Quality assessment of quantum teleportation through the distribution of fidelity
• Bounding Real Tensor Optimizations via the Numerical Range