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UID:0-1039@lptms.universite-paris-saclay.fr
DTSTART;TZID=Europe/Paris:20250620T140000
DTEND;TZID=Europe/Paris:20250620T150000
DTSTAMP:20250425T082816Z
URL:https://www.lptms.universite-paris-saclay.fr/seminars/informal-quantum
 -seminar-matteo-brunelli-college-de-france/
SUMMARY:Informal quantum seminar: Matteo Brunelli (Collège de France) - Sa
 lle des séminaires du FAST et du LPTMS\, bâtiment Pascal n°530 - 20 Jui
 n 25 14:00
DESCRIPTION:Nonreciprocal quantum matter\n&nbsp\;\nMatteo Brunelli (Collèg
 e de France)\n&nbsp\;\n\nNonreciprocal interactions\, in which an agent A 
 attracts another agent B while B repels A\, lead to exciting phenomena in 
 classical systems\, such as novel phase transitions and time-crystal behav
 ior. Whether such phenomena occur in quantum many-body systems remains to 
 a large extent an open question. In this talk\, I will discuss how nonreci
 procal interactions can be engineered in interacting quantum systems. I wi
 ll present a model of two ensembles of driven quantum spins featuring attr
 action-repulsion type interactions\, analogous to predator-prey dynamics. 
 The model can be realized with two atomic ensembles coupled via chiral wav
 eguides. In the thermodynamic limit\, nonreciprocal interactions result in
  a nonreciprocal phase transition into time-crystalline states\, associate
 d with spontaneous breaking of parity-time symmetry. Continuous monitoring
  of the waveguide’s output field also induces a time-crystal state in fi
 nite-size systems\, where parity-time symmetry is spontaneously broken\, a
 nd the corresponding quantum trajectories reveal quantum traveling-wave st
 ates. I will then show that nonreciprocal interactions arise in a model of
  superradiant laser in which a fraction of the atoms are not driven\, resu
 lting in frequency shift and spectral broadening of the emitted radiation.
  This represents a fundamental limitation for the operation of super radia
 nt lasers ultra-stable frequency reference.
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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TZID:Europe/Paris
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DTSTART:20250330T030000
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