Quantum speed limit for Kirkwood–Dirac quasiprobabilities
Year: 2025
Type: article
Abstract: What is the minimal time until a quantum system undergoing unitary dynamics can exhibit genuine quantum features? To answer this question we derive quantum speed limits (QSLs) for two-time correlation functions arising from statistics of measurements. These two-time correlators are described by Kirkwood–Dirac quasiprobabilities, if the initial quantum state of the system does not commute with the measurement observables. The QSLs here introduced are derived from the Schrödinger–Robertson uncertainty relation, and set the minimal time at which the real part of a quasiprobability can become negative and the corresponding imaginary part can be different from zero or crosses a given threshold. This departure of Kirkwood–Dirac quasiprobabilities from positivity is evidence for the onset of non-classical traits in the quantum dynamics. As an illustrative example, we apply these results to a conditional quantum gate by determining the optimal condition that gives rise to non-classicality at maximum speed. In this way, our analysis hints at boosted power extraction due to genuinely non-classical dynamics.
Source: Quantum Science and Technology
Institutions: University of Lisbon, Instituto de Telecomunicações, Instituto Superior Técnico, Centro de Física da Universidade de Coimbra, University of Coimbra, University of Maryland, Baltimore County, European Laboratory for Non-Linear Spectroscopy, National Institute of Optics, University of Florence
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,895
Funders: National Science Foundation, John Templeton Foundation, “la Caixa” Foundation, European Commission, Ministero dell’Istruzione, dell’Università e della Ricerca, Fundación Bancaria Caixa d'Estalvis i Pensions de Barcelona, Abdul Latif Jameel Water and Food Systems Lab, Massachusetts Institute of Technology, Fundação para a Ciência e a Tecnologia, Division of Materials Research, NextGenerationEU
Awards: G2001838499, G2150551741, G229093490, G2935071473, Centro de Física da Universidade de Coimbra, Maryland Quantum-Thermodynamics Hub: Decoherence and Equilibration in Quantum Systems, Stochastic Thermodynamics of Nonlinear Quantum Systems, G5443090575, G6347607356, G6489768745, G683440905, G6997658380, Centro de Física da Universidade de Coimbra, G743460029, G777498305, G8054906036, G972786147
OpenAlex ID: W4410142804