ELFT HÍRADÓ

[Janos Asboth <asboth AT phy.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

március 19. péntek 10h15,
online a Microsoft Teams-ben
<https://teams.microsoft.com/l/meetup-join/19%3a35c712c192104aa998ed6bab3f0cbc07%40thread.tacv2/1616006317709?context=%7b%22Tid%22%3a%226a3548ab-7570-4271-91a8-58da00697029%22%2c%22Oid%22%3a%22c7eaf7d2-684b-4597-b217-6a9121400219%22%7d>
Lovas Izabella (TU München):
Non-local emergent hydrodynamics in a long-range quantum spin system

Generic short-range interacting quantum systems with a conserved quantity
exhibit universal diffusive transport at late times. We show how this
universality is replaced by a more general superdiffusive transport process
in the presence of long-range interactions, decaying algebraically with
distance. While diffusive behavior is recovered for a sufficiently fast
decay, longer-ranged couplings give rise to an effective classical Levy
flight,  a random walk with step sizes following a heavy-tailed
distribution. We study this phenomenon in a long-range interacting XY spin
chain with conserved total magnetization, at infinite temperature. We
investigate the dynamics by employing non-equilibrium quantum field theory
and semi-classical phase space simulations. We find that the space-time
dependent spin density profiles are self-similar, and show superdiffusive
spreading, with scaling functions given by the stable symmetric
distributions. We also extract the associated generalized diffusion
constant, and demonstrate that it follows the prediction of classical Levy
flights; quantum many-body effects manifest themselves in an overall time
scale depending only weakly on the precise form of the algebraic long-range
interaction. Our findings can be readily verified with current trapped ion
experiments.

Minden érdeklődőt szeretettel várunk.

Asbóth János
szemináriumi koordinátor