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arXiv · 2309.06836

Advantages of the Kirkwood-Dirac distribution among general quasi-probabilities for finite-state quantum systems

Shun Umekawa·Jaeha Lee·Naomichi Hatano
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Abstract

We investigate features of the quasi-joint-probability distribution for finite-state quantum systems, especially the two-state and three-state quantum systems, comparing different types of quasi-joint-probability distributions based on the general framework of quasi-classicalization. We show from two perspectives that the Kirkwood-Dirac distribution is the quasi-joint-probability distribution that behaves nicely for the finite-state quantum systems. One is the similarity to the genuine probability and the other is the information that we can obtain from the quasi-probability. By introducing the concept of the possible values of observables, we show for the finite-state quantum systems that the Kirkwood-Dirac distribution behaves more similarly to the genuine probability distribution in contrast to most of the other quasi-probabilities including the Wigner function. We also prove that the states of the two-state and three-state quantum systems can be completely distinguished by the Kirkwood-Dirac distribution of only two directions of the spin and point out for the two-state system that the imaginary part of the quasi-probability is essential for the distinguishability of the state.

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Shun Umekawa, Jaeha Lee, Naomichi Hatano. 2023-09-13. Advantages of the Kirkwood-Dirac distribution among general quasi-probabilities for finite-state quantum systems. https://doi.org/10.1093/ptep%2Fptae005

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