BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//FeRMI - ECPv6.15.20//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-WR-CALNAME:FeRMI
X-ORIGINAL-URL:https://fermi.univ-tlse3.fr
X-WR-CALDESC:Évènements pour FeRMI
REFRESH-INTERVAL;VALUE=DURATION:PT1H
X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:Europe/Paris
BEGIN:DAYLIGHT
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:20220327T010000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:20221030T010000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:20230326T010000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:20231029T010000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:20240331T010000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:20241027T010000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20230905T140000
DTEND;TZID=Europe/Paris:20230905T153000
DTSTAMP:20260422T125436
CREATED:20230905T082109Z
LAST-MODIFIED:20230905T082109Z
UID:9192-1693922400-1693927800@fermi.univ-tlse3.fr
SUMMARY:Deux modèles de spin aux propriétés inattendues - (Haruki Watanabe / LPT / Seminar). - 05/09/2023\, 14H
DESCRIPTION:Haruki Watanabe (EUniversité de Tokyo) \nSeminar LPT\, 05/09/2023\, 14H\, 3R1\, seminar room\, 3rd floor \nSummary : \nIn this talk\, I will introduce two series of simple spin models with unusual properties. The first one is a modified Toric code that may have a unique ground state under periodic boundary condition\, despite its nontrivial topological order dictated by nontrivial entanglement entropy and anyonic excitations. The second one is a spin chain in which a U(1) symmetry may be spontaneously broken at T=0\, although naively such a phase is prohibited by the Hohenberg-Mermin-Wagner theorem. These examples will help our general understanding of quantum many-body systems and complete classification of possible phases of matter.
URL:https://fermi.univ-tlse3.fr/event/deux-modeles-de-spin-aux-proprietes-inattendues-haruki-watanabe-lpt-seminar-05-09-2023-14h/
LOCATION:salle de séminaire 3ème étage\, Bâtiment 3r1 Université Toulouse III\, Toulouse\, 31400\, France
CATEGORIES:Events,LPT,Seminars
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20230919T140000
DTEND;TZID=Europe/Paris:20230919T153000
DTSTAMP:20260422T125436
CREATED:20230918T084218Z
LAST-MODIFIED:20230919T064713Z
UID:9177-1695132000-1695137400@fermi.univ-tlse3.fr
SUMMARY:High-order diagrammatic expansion around BCS Hamiltonians : Polarized superfluid phase of the attractive Hubbard model - (Félix Werner / LPT / Seminar). - 19/09/2023\, 14H
DESCRIPTION:Félix Werner (ENS\, LKB) \nSeminar LPT\, 19/09/2023\, 14H\, 3R1\, seminar room\, 3rd floor \nSummary : \nIn contrast to conventional QMC methods\, expansions of intensive quantities in series of connected Feynman diagrams can be formulated directly in the thermodynamic limit. Over the last decade\, diagrammatic Monte Carlo algorithms made it possible to reach large expansion orders and to obtain state-of-the-art results for various models of interacting fermions in 2 and 3 dimensions\, mostly in the normal phase. \nWe obtained first results inside a superconducting phase\, for the 3D attractive Hubbard model [1]. Spontaneous symmetry breaking is implemented by expanding around a BCS Hamiltonian. All diagrams up to 12 loops are summed thanks to the connected determinant algorithm [2] with anomalous propagators. Working on the BCS side of the strongly correlated regime\, we observe convergence of the expansion\, and benchmark the results against determinant diagrammatic Monte Carlo [3]. In presence of a polarizing Zeeman field (where unbiased benchmarks are unavailable due to the fermion sign problem) we observe a first-order superconducting-to-normal phase transition\, and a thermally activated polarization of the superconducting phase well captured by a quasiparticle description. We also discuss the large-order behavior of the expansion and its relation to Goldstone and instanton singularities. \n\n[1] G. Spada\, R. Rossi\, F. Simkovic\, R. Garioud\, M. Ferrero\, K. Van Houcke\, F. Werner\, arXiv:2103.12038\n[2] R. Rossi\, PRL 119\, 045701 (2017)\n[3] E. Burovski\, N. Prokof’ev\, B. Svistunov\, M. Troyer\, PRL 96\, 160402 (2006)
URL:https://fermi.univ-tlse3.fr/event/tba-felix-werner-lpt-seminar-19-09-2023-14h/
LOCATION:salle de séminaire 3ème étage\, Bâtiment 3r1 Université Toulouse III\, Toulouse\, 31400\, France
CATEGORIES:Events,LPT,Seminars
END:VEVENT
END:VCALENDAR