Quasi-probability distributions for observables in dynamic systems

Hofer, Patrick P.. (2017) Quasi-probability distributions for observables in dynamic systems. Quantum, 1. p. 32.

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Official URL: https://edoc.unibas.ch/82994/

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We develop a general framework to investigate fluctuations of non-commuting observables. To this end, we consider the Keldysh quasi-probability distribution (KQPD). This distribution provides a measurement-independent description of the observables of interest and their time-evolution. Nevertheless, positive probability distributions for measurement outcomes can be obtained from the KQPD by taking into account the effect of measurement back-action and imprecision. Negativity in the KQPD can be linked to an interference effect and acts as an indicator for non-classical behavior. Notable examples of the KQPD are the Wigner function and the full counting statistics, both of which have been used extensively to describe systems in the absence as well as in the presence of a measurement apparatus. Here we discuss the KQPD and its moments in detail and connect it to various time-dependent problems including weak values, fluctuating work, and Leggett-Garg inequalities. Our results are illustrated using the simple example of two subsequent, non-commuting spin measurements.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Theoretical Quantum Physics (Potts)
UniBasel Contributors:Potts, Patrick
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:11 May 2021 09:44
Deposited On:11 May 2021 09:42

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