BEGIN:VCALENDAR
VERSION:2.0
PRODID:researchseminars.org
CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:Michael Fleischhauer (Dept. of Physics & research center OPTIMAS\,
  Univ. of Kaiserslautern\, Germany)
DTSTART:20210607T160000Z
DTEND:20210607T170000Z
DTSTAMP:20260423T024740Z
UID:QM3/47
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QM3/47/">Top
 ology of mixed states</a>\nby Michael Fleischhauer (Dept. of Physics & res
 earch center OPTIMAS\, Univ. of Kaiserslautern\, Germany) as part of Quant
 um Matter meets Maths (IST\, Lisbon)\n\n\nAbstract\nTopological states of 
 matter have fascinated physicists since a long time. The notion of topolog
 y is however ususally associated with ground states of (many-body)-Hamilto
 nians\, which are pure. So what is left of it at finite temperatures and c
 an topological protection be extended to non-equilibrium steady states (NE
 SS) of open systems? Can suitable observables be constructed that preserve
  the integrity of topological invariants for mixed states and what are mea
 surable consequences of their existence? Can we classify the topology of f
 inite-temperature and NESS using generalized symmetries? Motivated by topo
 logical charge pumps\, first introduced by Thouless\, I will first discuss
  a topological invariant for systems that break time reversal symmetry bas
 ed on the many-body polarization\, called ensemble geometric phase (EGP) [
 1]. In contrast to charge transport\, the EGP can be used to probe topolog
 y in one dimensional non-interacting [2] and interacting [3]\, closed and 
 open systems alike. Furthermore different from other constructions\, such 
 as the Uhlmann phase\, it can be extended to two dimensions [4]. I will th
 en extend the definition to systems with time-reversal symmetry and finall
 y talk about measurable consequences of mixed-states topological invariant
 s.\n\n[1] C.E. Bardyn\, L. Wawer\, A. Altland\, M. Fleischhauer\, S.Diehl\
 ,  (PRX 2018)\n\n[2] D. Linzner\, L. Wawer\, F. Grusdt\, M. Fleischhauer\,
  (PRB 2016)\n\n[3] R. Unanyan\, M. Kiefer-Emmanouilidis\, M. Fleischhauer\
 , (PRL 2020)\n\n[4] L. Wawer\, M. Fleischhauer\, arxiv 2104.12115\n
LOCATION:https://researchseminars.org/talk/QM3/47/
END:VEVENT
END:VCALENDAR