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UID:0-1111@lptms.universite-paris-saclay.fr
DTSTART;TZID=Europe/Paris:20260519T110000
DTEND;TZID=Europe/Paris:20260519T120000
DTSTAMP:20260512T150408Z
URL:https://www.lptms.universite-paris-saclay.fr/seminars/lptms-seminar-th
 ibault-scoquart-lpt-toulouse/
SUMMARY:LPTMS Seminar: Thibault Scoquart (LPT\, Toulouse) - Salle des sémi
 naires du FAST et du LPTMS\, bâtiment Pascal n°530 - 19 Mai 26 11:00
DESCRIPTION:Many-body localization through imbalance statistics: transition
  scaling and rare resonances\nThibault Scoquart (LPT\, Toulouse)\n&nbsp\;\
 n\nMany-body localization (MBL) is a remarkable phenomenon where interacti
 ng quantum systems fail to thermalize due to disorder. Despite two decades
  of intense theoretical and numerical work\, there is still no clear conse
 nsus on whether a true 1D MBL phase exists in the thermodynamic limit\, or
  whether it eventually gives way to slow thermalization.\n\nAfter a broad 
 introduction to the current open questions surrounding MBL\, I will explai
 n why the fate of the localized regime is\, at its core\, controlled by th
 e system's ability to form resonances across the exponentially large many-
 body Hilbert space -- pairs of configurations close in energy and coupled 
 by interactions. A growing consensus in the literature is that the relevan
 t resonances are rare events\, both in real space and in Fock space\, whic
 h is why disorder-averaged quantities can be misleading: the physics of MB
 L hides in the fluctuations and distributions of dynamical observables.\n\
 nI will illustrate this through recent work on the imbalance\, a standard 
 dynamical probe of the memory of an initial state in MBL experiments\, exa
 mined at two complementary levels. Across a family of disordered spin mode
 ls with different Fock-space correlation structures [1]\, I will first sho
 w how the scaling of the MBL crossover with system size is faithfully trac
 ked by the quantum and mesoscopic fluctuations of a "generalized" imbalanc
 e\, yielding finite-size phase diagrams and transition widths in agreement
  with spectral observables [2]. I will then turn to the deep localized reg
 ime\, where we recently showed that the standard\, site-averaged imbalance
  hides a much richer microscopic structure: the full distribution of site-
 resolved imbalances exhibits direct fingerprints of rare local resonances 
 between a few neighboring spins\, quantitatively captured by a simple anal
 ytical toy model [3].\n\n[1] T. Scoquart\, I. Gornyi and A. Mirlin\, Phys.
  Rev. B 109\, 214203 (2024)\n[2] T. Scoquart\, I. Gornyi and A. Mirlin\, P
 hys. Rev. B 112\, 064203 (2025)\n[3] A. Haldar\, T. Scoquart\, F. Alet and
  N. Laflorencie\, arXiv:2601.05177 (2026)
CATEGORIES:seminars
LOCATION:Salle des séminaires du FAST et du LPTMS\, bâtiment Pascal n°53
 0\, rue André Riviere\, Orsay\, 91405\, France
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=rue André Riviere\, Orsay\
 , 91405\, France;X-APPLE-RADIUS=100;X-TITLE=Salle des séminaires du FAST 
 et du LPTMS\, bâtiment Pascal n°530:geo:0,0
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DTSTART:20260329T030000
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