Conferences
Selection of international conferences where I presented my work.
American Physical Society (APS) March Meeting 2016, Baltimore, Maryland
Title: Short- and long-time dynamics of isolated many-body quantum systems (link)
Speaker: Marco Tavora
Description: We show our results for the relaxation process of isolated interacting quantum spin chains in the integrable and chaotic regimes. The dynamics of the survival probability (the probability for finding the system still in its initial state at later times) and of few-body observables are analyzed. Different time scales are considered. While the short-time evolution is determined by the shape of the weighted energy distribution of the initial state, the long-time behavior depends on the bounds of the spectrum.~ Both numerical and analytical results are presented as well as comparisons with existing rigorous mathematical derivations. We consider initial states that can be prepared in experiments with cold atoms in optical lattices.
Supported by the National Science Foundation (NSF-DMR 1004589)
American Physical Society (APS) Division of Atomic, Molecular and Optical Physics Meeting (DAMOP) 2016; Providence, RI
Title: Power-law Decays and Thermalization in Isolated Many-Body Quantum Systems (link)
Speaker: Marco Tavora
Description: We propose a new criterion for thermalization in isolated many-body quantum systems. It is based on the powerlaw behavior of the survival probability at long times. The value of the powerlaw exponent depends on the shape and filling of the energy distribution of the initial state. Exponents larger than or equal to 2 correspond to ergodic filling and consequent thermalization. We show that the algebraic behavior, which occurs in both integrable and chaotic systems, may be caused by bounds in the spectrum or by the presence of correlations between the eigenstates of the Hamiltonian. Numerical and analytical results as well as comparisons with existing rigorous mathematical derivations are presented. Our focus are on initial states that can be prepared experimentally using cold atoms in optical lattices.
Supported by the National Science Foundation (NSF Grant No. DMR-1147430)
American Physical Society (APS) March Meeting 2015; San Antonio, Texas
Title: Quench dynamics of one-dimensional interacting bosons in a disordered potential: Elastic dephasing and critical speeding-up of thermalization (link)
Speaker: Marco Tavora
Description: The dynamics of interacting bosons in one dimension following the sudden switching on of a weak disordered potential is investigated. On time scales before quasiparticles scatter (prethermalized regime), the dephasing from random elastic forward scattering causes all correlations to decay exponentially fast, but the system remains far from thermal equilibrium. For longer times, the combined effect of disorder and interactions gives rise to inelastic scattering and to thermalization. A novel quantum kinetic equation accounting for both disorder and interactions is employed to study the dynamics. Thermalization turns out to be most effective close to the superfluid-Bose glass critical point where nonlinearities become more and more important. The numerically obtained thermalization times are found to agree well with analytic estimates.
Supported by the National Science Foundation (NSF DMR 1303177)
American Physical Society (APS) March Meeting 2013; Baltimore, Maryland
Title: Quench dynamics in the one-dimensional sine-Gordon model: Quantum kinetic equation approach (link)
Speaker: Marco Tavora
Description: We study dynamics after a quantum quench in the one-dimensional sine-Gordon model in its gapless phase. We construct the Dyson equation to leading (quadratic) order in the cosine potential and show that the resulting quantum kinetic equation is atypical in that it involves multi-particle scattering processes. We also show that using an effective action, which generates the Dyson equation by a variational principle, the conserved stress-momentum tensor can be constructed. We solve the dynamics numerically by making a quasi-classical approximation that makes the quantum kinetic equation local in time while retaining the multi-particle nature of the scattering processes. We find that the boson distribution function reaches a steady-state characterized by an effective temperature in the long-wavelength limit. We present an analytic argument for the value of the effective temperature and the time-scales to reach this steady-state.
Supported by the National Science Foundation (NSF-DMR 1004589)