Nonlocal emergent hydrodynamics in a long-range quantum spin system

Dokumenttyp:: Zeitschriftenaufsatz
Autor(en):: Schuckert, Alexander; Lovas, Izabella; Knap, Michael
Titel:: Nonlocal emergent hydrodynamics in a long-range quantum spin system
Abstract:: Generic short-range interacting quantum systems with a conserved quantity exhibit universal diffusive transport at late times. We employ nonequilibrium quantum field theory and semiclassical phase-space simulations to show how this universality is replaced by a more general transport process in a long-range XY spin chain at infinite temperature with couplings decaying algebraically with distance as r−α. While diffusion is recovered for α>1.5, longer-ranged couplings with 0.5<α≤1.5 give rise to effective classical Lévy flights, a random walk with step sizes drawn from a distribution with algebraic tails. We find that the space-time-dependent spin density profiles are self-similar, with scaling functions given by the stable symmetric distributions. As a consequence, for 0.5<α≤1.5, autocorrelations show hydrodynamic tails decaying in time as t−1/(2α−1) and linear-response theory breaks down. Our findings can be readily verified with current trapped ion experiments.
Zeitschriftentitel:: Physical Review B 2020-01
Jahr:: 2020
Band / Volume:: 101
Heft / Issue:: 2
Volltext / DOI:: doi:10.1103/physrevb.101.020416
Verlag / Institution:: American Physical Society (APS)
E-ISSN:: 2469-99502469-9969
Publikationsdatum:: 28.01.2020
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