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SUMMARY:Anton Kapustin (Caltech)
DTSTART:20210427T150000Z
DTEND:20210427T160000Z
DTSTAMP:20260404T110912Z
UID:IHES-Quantum-Encounters/1
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/IHES-
 Quantum-Encounters/1/">Noncommutative geometry of quantum lattice models a
 nd the higher Berry phase</a>\nby Anton Kapustin (Caltech) as part of IHES
  Quantum Encounters\n\n\nAbstract\nRecently methods of quantum statistical
  mechanics have been fruitfully applied to the study of phases of quantum 
 lattice systems at zero temperature. For example\, a rigorous definition o
 f a Short-Range Entangled phase of matter has been given and a classificat
 ion of such phases in one spatial dimension has been achieved. I will disc
 uss some of these developments\, focusing on the topology and geometry of 
 the space of Short-Range Entangled states. According to a conjecture of A.
  Kitaev\, these spaces form a loop spectrum in the sense of homotopy theor
 y. This conjecture implies that to any family of Short-Range entangled sta
 tes in one dimension one can associate a gerbe on the parameter space. I w
 ill show how to construct such a gerbe. Thе curvature of this gerbe is a 
 closed 3-form with quantized periods and can be regarded as a higher-dimen
 sional generalization of the curvature of the Berry connection.\n\nSee sem
 inar webpage https://seminars.ihes.fr/quantum/ for the zoom link\n
LOCATION:https://stable.researchseminars.org/talk/IHES-Quantum-Encounters/
 1/
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SUMMARY:Peter C.W. Holdsworth (Ecole Normale Supérieure de Lyon)
DTSTART:20210601T140000Z
DTEND:20210601T150000Z
DTSTAMP:20260404T110912Z
UID:IHES-Quantum-Encounters/2
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/IHES-
 Quantum-Encounters/2/">Emergence: from spins to charges</a>\nby Peter C.W.
  Holdsworth (Ecole Normale Supérieure de Lyon) as part of IHES Quantum En
 counters\n\n\nAbstract\nEmergence is a major buzz word of our times. My wo
 rking definition\, which gives plenty of room for manoeuvre is: the appear
 ance of many body phenomena of higher symmetry than that of the Hamiltonia
 n and degrees of freedom at the microscopic level.\n\nIn this colloquium I
  will discuss a topical example - the frustrated magnetic material\, spin 
 ice. Here\, to an excellent approximation a classical field theoretic desc
 ription with continuous U(1) symmetry emerges from Ising like degrees of f
 reedom. The associated quasi-particles appear to be freely moving magnetic
  charge - magnetic monopoles - and the system behaves as a magnetic Coulom
 b fluid in the grand canonical ensemble with intrinsic topological propert
 ies. With the addition of quantum fluctuations the emergent magneto-static
 s develops further into a complete analogue of quantum electrodynamics. I 
 will aliment this discussion with experimental results from a wide range o
 f systems.\n\nSee the zoom link at https://indico.math.cnrs.fr/event/6687/
 \n
LOCATION:https://stable.researchseminars.org/talk/IHES-Quantum-Encounters/
 2/
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