Joint ICTP/SISSA Condensed Matter Seminar, 18 April at 11:00am, Federica Surace

[CMSP Seminars Secretariat]

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  Joint ICTP/SISSA Condensed Matter Seminar
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** * * Tuesday**, 18 April 2023, 11:00**am ***(CET)** * **
In person: *Luigi Stasi Seminar Room **(Leonardo Building, second floor)***
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/Zoom: 
https://zoom.us/meeting/register/tJYudOisqzspGNALyT5pD1RmCY96qUiJ2Ztv/<https://zoom.us/meeting/register/tJIsfuuhqjsrE9EZY2loNxNobg8Lf39NUVHJ>

Speaker: *Federica Surace *(California Institute of Technology)

Title: *Weak perturbations of integrable models

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Abstract:
A quantum integrable system slightly perturbed away from integrability 
is typically expected to thermalize on timescales of order τ∼λ^-2 , 
where λ is the perturbation strength. We here study classes of 
perturbations that violate this scaling, and exhibit much longer 
thermalization times τ∼λ^-2k where k>1 is an integer.  Systems with 
these "weak integrability breaking'' perturbations have an extensive 
number of quasi-conserved quantities that commute with the perturbed 
Hamiltonian up to corrections of order λ^k . We demonstrate a systematic 
construction to obtain families of such weak perturbations of a generic 
integrable model for arbitrary k. We then apply the construction to 
various models, including the Heisenberg, XXZ, and XYZ chains, the 
Hubbard model, models of spinless free fermions, and the quantum Ising 
chain. Our analytical framework explains the previously observed 
evidence of weak integrability breaking in the Heisenberg and XXZ chains 
under certain perturbations.