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arXiv · 1710.01565

Optimal convex approximations of quantum states

Massimiliano F. Sacchi
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Abstract

We consider the problem of optimally approximating an unavailable quantum state $ρ$ by the convex mixing of states drawn from a set of available states $\{ ν_i\}$. The problem is recast to look for the least distinguishable state from $ρ$ among the convex set $\sum_i p_i ν_i$, and the corresponding optimal weights $\{ p_i \}$ provide the optimal convex mixing. We present the complete solution for the optimal convex approximation of a qubit mixed state when the set of available states comprises the three bases of the Pauli matrices.

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Massimiliano F. Sacchi. 2019-01-23. Optimal convex approximations of quantum states. https://doi.org/10.1103/physreva.96.042325

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