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UID:0-952@lptms.universite-paris-saclay.fr
DTSTART;TZID=Europe/Paris:20240423T110000
DTEND;TZID=Europe/Paris:20240423T120000
DTSTAMP:20240415T112902Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm
 s-alessio-lerose-university-of-oxford/
SUMMARY:Séminaire du LPTMS : Alessio Lerose (University of Oxford) - Salle
  des séminaires du FAST et du LPTMS\, bâtiment Pascal n°530 - 23 Avr 24
  11:00
DESCRIPTION:Theory of robust ergodicity breaking in quantum many-body syste
 ms with long-range interactions\nAlessio Lerose (University of Oxford)\nRe
 cent years have seen the discovery of a number of routes to (strong or wea
 k forms of) ergodicity breaking in isolated quantum many-body systems\, ev
 en in absence of quenched disorder. Quantum many-body scars (QMBS) - excep
 tional energy eigenstates associated with violations of thermalization for
  special non-equilibrium initial states - rank as a novel remarkable possi
 bility. The various systematic constructions of QMBS\, however\, require f
 ine-tuning of local Hamiltonian parameters. In this talk I will demonstrat
 e that long-range interacting quantum spin lattices generically host robus
 t QMBS. This result is based on an analysis of spectral properties upon ra
 ising the power-law decay exponent α of spin-spin interactions from the s
 olvable permutationally-symmetric limit α=0:\n\n 	Firstly we numerically 
 establish that\, despite spectral signatures of quantum chaos appear for i
 nfinitesimal α\, the towers of α=0 energy eigenstates with large collect
 ive spin are smoothly deformed as α is increased\, and exhibit characteri
 stic QMBS features.\n 	 To elucidate the nature and fate of these states 
 in larger systems we introduce a novel analytical approach based on mappin
 g the quantum spin Hamiltonian onto a relativistic quantum rotor non-linea
 rly coupled to an extensive set of bosonic modes. We provide an original e
 xact solution for the eigenstates of this interacting impurity model\, and
  show their self-consistent localization in large-spin sectors of the orig
 inal spin Hamiltonian for 0&lt\;α&lt\;d.\n\nOur theory unveils the stabil
 ity mechanism of such QMBS for arbitrary system size\, and predicts instan
 ces of its breakdown e.g. near dynamical critical points or in presence of
  semiclassical chaos\, which we verify numerically in long-range quantum I
 sing chains. As a byproduct\, we find a predictive criterion for absence o
 f heating under periodic driving beyond existing Floquet-prethermalization
  theorems. I will finally briefly discuss how the multipartite entanglemen
 t structure of the persistent non-equilibrium states discovered here has p
 otential metrological applications in present-day experimental platforms.\
 n\nMain Ref: https://arxiv.org/abs/2309.12504
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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