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TZID:Europe/Paris
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UID:0-1154@lptms.universite-paris-saclay.fr
DTSTART;TZID=Europe/Paris:20260904T140000
DTEND;TZID=Europe/Paris:20260904T151500
DTSTAMP:20260902T135005Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/informal-quantum-
 seminar-zeijan-li/
SUMMARY:Informal Quantum Seminar: Zeijan Li - Salle des séminaires du FAST
  et du LPTMS\, bâtiment Pascal n°530 - 4 Sep 26 14:00
DESCRIPTION:Driven-dissipative spin systems: semiclassical approximations a
 nd beyond \nZeijan Li (Paris Cité)\n&nbsp\;\n\nThe investigation of open
  quantum many-body systems is usually hindered by the “curse of dimensio
 nality” and requires appropriately designed approximation tools. In the 
 context of spin systems\, I will first introduce a semiclassical framework
  for solving open quantum dynamics [1\,2]. The method consists of generali
 zed spin-wave approximations applied to quantum trajectories unraveled fro
 m the Lindblad master equation\, and generally applies to regimes beyond t
 he reach of conventional spin-wave theories\, including short-range intera
 ctions and local quantum jumps\, enabling the efficient simulation of larg
 e-scale interacting spins. I will demonstrate the approach by considering 
 a variable-range driven-dissipative Ising model on a 2D lattice\, and show
  that the interaction range alters the universality class of the criticali
 ty in a Z2 symmetry breaking dissipative phase transition. I will then dis
 cuss how this semiclassical description can be naturally “upgraded” to
  capture the exact Lindblad dynamics via a multi-configuration ansatz in t
 he framework of time-dependent variational principle [3]\,  where the equ
 ation of motion can be assembled analytically (without any need for Monte-
 Carlo sampling like neural-network methods do) and efficiently solved. Fin
 ally (if time permits)\, I will introduce the extension of the above multi
 -configuration variational approach to the regime of stochastic quantum tr
 ajectories.\n\n[1] ZL\, A Delmonte\, R Fazio\, PRB 113\, 214324 (2026)\n[2
 ] ZL\, A Delmonte\, X Turkeshi\, R Fazio\, Nat. Commun. 16\, 4329 (2025)\n
 [3] J Tosca*\, ZL*\, et al\, arXiv:2604.01165 (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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