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TZID:Europe/Paris
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BEGIN:VEVENT
UID:1-487@lptms.universite-paris-saclay.fr
DTSTART:20170119T110000Z
DTEND:20170119T120000Z
DTSTAMP:20170110T120238Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm
 s-eric-vernier-seminaire-exceptionnel/
SUMMARY:Séminaire du LPTMS: Eric Vernier  *** séminaire exceptionnel *** 
 - LPTMS\, salle 201\, 2ème étage\, Bât 100\, Campus d'Orsay - 19 Jan 17
  11:00
DESCRIPTION:Non equilibrium dynamics of quantum systems : the Loschmidt ech
 o\nEric Vernier (SISSA\, Trieste)\nThe non-equilibrium dynamics of quantum
  many-body systems has attracted a large interest over  the last decade\,
  prompted by formidable advances in cold-atomic experiments.  While much 
 progress has been done in understanding the relaxation mechanisms of physi
 cal observables and the characterization of the stationary state following
 \, for instance\, a quantum quench (where an isolated system is let evolve
  after one or several parameters have been suddenly changed)\, very few an
 alytical results exist about the full time dynamics despite the existence 
 of prototypical integrable models. Indeed\, the time dynamics involves con
 tributions for arbitrarily excited eigenstates of the Hamiltonian\, making
  calculations prohibitively difficult.\n\nIn this talk I will present some
  progress made recently in this direction (based on the preprint arXiv:161
 1.06126)\, namely an analytical computation of the Loschmidt echo\, which 
 measures the overlap between the state of the system at a given time and i
 ts initial state\, for various types of quenches in the Heisenberg XXZ spi
 n chain. The latter has attracted a renewed interest recently in the conte
 xt of dynamical phase transitions\, which it signals through its non-analy
 ticities as a function of the time. Using a reformulation of the problem i
 n terms of an auxiliary boundary quantum transfer matrix and using an infi
 nite set of functional relations\, we write the Loschmidt echo as the solu
 tion of an infinite set of Non Linear Integral Equations\, which allows fo
 r its exact determination at arbitrarily large time. This method overcomes
  the time limitations experienced by numerical approaches\, and may serve 
 as a basis for the computation of other physical observables.\n&nbsp\;
CATEGORIES:seminars
LOCATION:LPTMS\, salle 201\, 2ème étage\, Bât 100\, Campus d'Orsay\, 15 
 Rue Georges Clemenceau\, Orsay\, 91405\, France
GEO:48.698185;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  Orsay\, 91405\, France;X-APPLE-RADIUS=100;X-TITLE=LPTMS\, salle 201\, 2è
 me étage\, Bât 100\, Campus d'Orsay:geo:48.698185,2.181768
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