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SUMMARY:Thermalization and its absence in the XX spin chain model
DTSTART:20260827T113000Z
DTEND:20260827T120000Z
DTSTAMP:20261007T062500Z
UID:indico-event-398@indico.physik.uni-bielefeld.de
DESCRIPTION:Speakers: Christian Eidecker-Dunkel\n\nA quantum quench often 
 consists in the following setup: Some system is initially prepared in an e
 quilibrium state of Hamiltonian Hg=H−gV\, subject to a (small) parameter
  change at time t=0\, and evolves in time with Hamiltonian H for times t>0
 . In such a setup\, [1] rigorously established that the relaxation behavio
 r of (the expectation values of) some observable A can be approximated by 
 a series of correlations of A and V in the equilibrium pertaining to H. Mo
 re precisely speaking\, it was shown that the approximation is exact up to
  a finite error independent of the time or system size\, and analytical up
 per bounds are available for many important cases. With this properties\, 
 said approximation forms a mighty tool for analytical studies of thermaliz
 ation and its absence. Taking the paradigmatic XX spin chain model with a 
 magnetic field as an example\, it could be shown that the XX model thermal
 izes whenever it is subject to a homogeneous magnetic field [2]. Turning a
 way from the homogeneous case\, it was shown that even one single inhomoge
 neity in the magnetic field might be sufficient to prevent thermalization 
 [3]. In my presentation\, I will briefly introduce the general framework o
 f [1]\, before presenting the results and implications of [2] and [3] in s
 ome detail. \n[1] P. Reimann and C. Eidecker-Dunkel\, Onsager’s regress
 ion hypothesis adjusted to quantum systems\, Phys. Rev. B 110\, 014306 (20
 24)[2] P. Reimann and C. Eidecker-Dunkel\, Thermalization in a simple spin
 -chain model\, Phys. Rev. B 111\, 054312 (2025)[3] P. Reimann and C. Eidec
 ker-Dunkel\, Absence of thermalization after a local quench and strong vio
 lation of the eigenstate thermalization hypothesis\, Phys. Rev. B 113\, 14
 4304 (2026)\n\nhttps://indico.physik.uni-bielefeld.de/event/398/
LOCATION:D5-153 (UHG)
URL:https://indico.physik.uni-bielefeld.de/event/398/
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