Seminar: Nicole Yunger Halpern (NIST, QuICS, University of Maryland); Wed 09 February 2022

Last updated February 28, 2022 by Dermot Green

09 February 2022, 4pm (time TBC)
Location: MS Teams online seminar

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

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 operators’ 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.

1) Arvidsson-Shukur, NYH, Lepage, Lasek, Barnes, and Lloyd, Nat. Comms. 11, 3775 (2020).
2) Arvidsson-Shukur, Drori-Chevalier, and NYH, J. Phys. A 54, 284001 (2021).
3) Lupu-Gladstein, Yilmaz, Arvidsson-Shukur, Brodutch, Pang, Steinberg, and NYH, arXiv:2111.01194 (2021).
4) NYH, Swingle, and Dressel, Phys. Rev. A 97, 042105 (2018).


We are a Research Cluster of the School of Mathematics and Physics at Queen’s University Belfast in Northern Ireland. Our research interests are focused primarily on computational and theoretical physics.

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The Old Physics Building,
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