Department of Physics & Astronomy
University of New Mexico

CQuIC Seminars

My favorite not-quite-probability distribution and its usefulness in metrology

Presented by Nicole Yunger Halpern, NIST/Maryland

Quasiprobability distributions resemble probability distributions but can contain negative and imaginary values. Such distributions represent quantum states as probability distributions over phase space represent states in classical statistical mechanics. Many quasiprobabilities exist, the most famous being the Wigner function. Among the least famous ranks the Kirkwood-Dirac distribution, discovered during the early 1900s and then forgotten. But the Kirkwood-Dirac distribution has been enjoying a renaissance recently: Applications range from quantum chaos to tomography, metrology, foundations, and thermodynamics. I will introduce the Kirkwood-Dirac distribution and illustrate its usefulness in metrology: The quasiprobability can be used to prove that operator' noncommmutation - a nonclassical phenomenon - underlies a protocol's effectiveness in phase estimation. I aim to convince you that the Kirkwood-Dirac distribution is the best little quasiprobability you'd never heard of.

3:30 pm, Thursday, February 10, 2022

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