Stabilizer entropies and nonstabilizerness monotones

• URL: http://arxiv.org/abs/2303.10152v2
• Date: Mon, 21 Aug 2023 08:29:26 GMT
• Title: Stabilizer entropies and nonstabilizerness monotones
• Authors: Tobias Haug, Lorenzo Piroli
• Abstract summary: We study different aspects of the stabilizer entropies (SEs) We compare them against known nonstabilizerness monotones such as the min-relative entropy and the robustness of magic. In addition to previously developed exact methods to compute the R'enyi SEs, we put forward a scheme based on perfect MPS sampling.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We study different aspects of the stabilizer entropies (SEs) and compare them against known nonstabilizerness monotones such as the min-relative entropy and the robustness of magic. First, by means of explicit examples, we show that, for R\'enyi index $0\leq n<2$, the SEs are not monotones with respect to stabilizer protocols which include computational-basis measurements, not even when restricting to pure states (while the question remains open for $n\geq 2$). Next, we show that, for any R\'enyi index, the SEs do not satisfy a strong monotonicity condition with respect to computational-basis measurements. We further study SEs in different classes of many-body states. We compare the SEs with other measures, either proving or providing numerical evidence for inequalities between them. Finally, we discuss exact or efficient tensor-network numerical methods to compute SEs of matrix-product states (MPSs) for large numbers of qubits. In addition to previously developed exact methods to compute the R\'enyi SEs, we also put forward a scheme based on perfect MPS sampling, allowing us to compute efficiently the von Neumann SE for large bond dimensions.

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