ELFT HÍRADÓ

[tcsaba <tcsaba AT eik.bme.hu>]

                 M E G H Í V Ó - I N V I T A T I O N

    Seminar Series of the Department of Theoretical Physics at the
           Budapest University of Technology and Economics


                         Maksym Serbyn
           (Institute of Science and Technology Austria)

   Quantum many-body scars, mixed phase spaces and non-universal 
thermalization


The statistical mechanics description of many-particle systems rests on 
the assumption of ergodicity, the ability of a system to explore all 
allowed configurations in the phase space. For quantum many-body systems 
statistical mechanics predicts the equilibration of highly excited 
non-equilibrium state towards a featureless thermal state. Hence, it is 
highly desirable to explore possible ways to avoid ergodicity in quantum 
systems. Many-body localization presents one generic mechanism for a 
strong violation of ergodicity relying on the presence of quenched 
disorder. In my talk I will discuss a different mechanism of the weak 
ergodicity breaking relevant for the experimentally realized 
Rydberg-atom quantum simulator [1]. This mechanism arises from the 
presence of special eigenstates in the many-body spectrum that are 
reminiscent of quantum scars in chaotic non-interacting systems [2]. I 
will construct the weak deformation of the Rydberg chain Hamiltonian 
that makes revivals virtually perfect [3]. In the second part of the 
talk I will provide a dynamical perspective on quantum scars. I will 
show the occurrence of mixed phase space within time-dependent 
variational principle (TDVP) description of dynamics. I will use TDVP to 
find new scars and explore their response to perturbations of the 
Hamiltonian. Finally, I will argue that the mixed phase space generally 
leads to non-universal dependence of thermalization on the initial state 
and discuss a new opportunities for the creation of novel states with 
long-lived coherence in systems that are now experimentally realizable 
[1].

[1] H. Bernien, et al., Nature 551, 579–584 (2017), arXiv:1707.04344
[2] C. J. Turner, A. A. Michailidis, D. A. Abanin, M. Serbyn, Z. Papić, 
Nature Physics (May 2018), arXiv:1711.03528 and Phys. Rev. B 98, 155134 
(2018) arXiv:1806.10933
[3] S. Choi, C. J. Turner, et al., arXiv:1812.05561

Időpont: 2019. május 3. péntek, 10:15
Helyszín: BME Fizikai Intézet, Elméleti Fizika Tanszék,
Budafoki út 8. F-épület, III lépcsőház, szemináriumi szoba