Anomalous quantum dynamics in scarred and integrable systems

Generic quantum systems are expected to reach local thermal equilibrium under their unitary dynamics starting from any initial state. This thesis presents scenarios in which such thermalization does not occur. Firstly, we establish the quantum integrability of the central spin-1 XX model by constructing its Bethe ansatz eigenstates and an extensive set of conserved charges. These charges prevent the central spin from thermalizing in quantum quenches. Secondly, using an irreducible tensor operator basis, we describe an approach to construct exhaustive families of Hamiltonians hosting quantum many-body scars, which are atypical, athermal eigenstates in the bulk of an otherwise thermalizing spectrum. As scars are equally spaced in energy, initial states launched in the scar manifold exhibit perfect revivals and evade thermalization. Finally, even in systems that thermalize, certain quasiparticles have anomalously long lifetimes at all temperatures. We explain this phenomenon as an approximate dynamical symmetry.

Author dc:creator

• Tang, Long Hin

Advisor dc:contributor.advisor

• Chandran, Anushya

• Physics

Statement dc:rights

• Attribution 4.0 International

Licence dc:rights.uri

• http://creativecommons.org/licenses/by/4.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

https://hdl.handle.net/2144/50873

OAI identifier oai:identifier

oai:open.bu.edu:2144/50873