Open this publication in new window or tab >>2023 (English)In: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 108, no 5, article id 052421Article in journal (Refereed) Published
Abstract [en]
Many quantum speed limits for isolated systems can be generalized to also apply to closed systems. This is, for example, the case with the well-known Mandelstam-Tamm quantum speed limit. Margolus and Levitin derived an equally well-known and ostensibly related quantum speed limit, and it seems to be widely believed that the Margolus-Levitin quantum speed limit can be similarly generalized to closed systems. However, a recent geometrical examination of this limit reveals that it differs significantly from most known quantum speed limits. In this paper, we show that, contrary to the common belief, the Margolus-Levitin quantum speed limit does not extend to closed systems in an obvious way. More precisely, we show that for every hypothetical bound of Margolus-Levitin type, there are closed systems that evolve with a conserved normalized expected energy between states with any given fidelity in a time shorter than the bound. We also show that for isolated systems, the Mandelstam-Tamm quantum speed limit and a slightly weakened version of this limit that we call the Bhatia-Davies quantum speed limit always saturate simultaneously. Both of these evolution time estimates extend straightforwardly to closed systems. We demonstrate that there are closed systems that saturate the Mandelstam-Tamm but not the Bhatia-Davies quantum speed limit.
Place, publisher, year, edition, pages
American Physical Society, 2023
Keywords
Closed systems, Evolution time, Expected energy, Isolated systems, Speed limit, Quantum theory
National Category
Physical Sciences
Research subject
Mathematics
Identifiers
urn:nbn:se:kau:diva-97684 (URN)10.1103/PhysRevA.108.052421 (DOI)2-s2.0-85178150097 (Scopus ID)
2023-12-112023-12-112023-12-11Bibliographically approved