Diverging Quantum Speed Limits: A Herald of Classicality

When is the quantum speed limit (QSL) really quantum? While vanishing QSL times often indicate emergent classical behavior, it still not entirely understood what precise aspects of classicality are at origin this dynamical feature. Here, we show that (or, equivalently, diverging speeds) can be traced back to reduced uncertainty in observables and thus as a consequence emerging for these particular observables. We illustrate mechanism by developing formalism continuous-variable systems undergoing general Gaussian dynamics. For systems, three typical scenarios leading times, namely large squeezing, small effective Planck’s constant, particle number, fundamentally connected each other. In contrast, studying dynamics open mixed states, emerges due incoherent mixing states from addition noise typically increases time.Received 21 July 2021Accepted 10 November 2021DOI:https://doi.org/10.1103/PRXQuantum.2.040349Published American Physical Society under terms Creative Commons Attribution 4.0 International license. Further distribution work must maintain attribution author(s) published article's title, journal citation, DOI.Published SocietyPhysics Subject Headings (PhySH)Research AreasQuantum controlQuantum information processingQuantum processing with continuous variablesQuantum Information