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SUMMARY:Chong Wang (PI)
DTSTART:20240312T150000Z
DTEND:20240312T160000Z
DTSTAMP:20260423T021140Z
UID:SymSem/59
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/SymSem/59/">
 Mixed-state quantum anomaly and multipartite entanglement</a>\nby Chong Wa
 ng (PI) as part of Symmetry Seminar\n\n\nAbstract\nQuantum entanglement me
 asures of many-body states have been increasingly useful to characterize p
 hases of matter. In this talk I will explore a surprising connection betwe
 en mixed state entanglement and 't Hooft anomaly. More specifically\, we c
 onsider lattice systems in d space dimensions with anomalous symmetry G wh
 ere the anomaly is characterized by an invariant in group cohomology. We s
 how that any mixed state ρ that is strongly symmetric under G\, in the se
 nse that Gρ~ρ\, is necessarily (d+2)-nonseparable\, i.e. is not the mixt
 ure of tensor products of (d+2) states in the Hilbert space. Furthermore\,
  such states cannot be prepared from any (d+2)-separable states using fini
 te-depth local quantum channels\, so the nonseparability is long-ranged in
  nature. We provide proof of these results in d<2\, and plausibility argum
 ents in higher dimensions.  The anomaly-nonseparability connection thus al
 lows us to generate simple examples of mixed states with nontrivial long-r
 anged multipartite entanglement\, even in d=1.\n
LOCATION:https://researchseminars.org/talk/SymSem/59/
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