7th Trieste–Ljubljana meeting @ SISSA

When: Tuesday, December 10th, 2019
Where: SISSA, First Floor, Room 128 (Cinema Room)

9:30–10:15 welcome coffee
10:15–10:50 Federica Surace (ICTP)
10:50–11:25 Žiga Krajnik (Ljubljana)
11:25–12:00 Andrea Colcelli (SISSA)
12:00–13:00 lunch
13:00–15:15 discussions
15:15–15:50 Spyros Sotiriadis (Ljubljana)
15:50–16:25 Giuseppe Di Giulio (SISSA)
16:25–17:00 Scott Taylor (ICTP)
17:00– discussions
Quasilocalized dynamics from confinement of quantum excitations
Speaker Federica Surace
Abstract Confinement of excitations induces quasilocalized dynamics in disorder-free isolated quantum many-body systems in one spatial dimension. This occurrence is signalled by severe suppression of quantum correlation spreading and of entanglement growth, long-time persistence of spatial inhomogeneities, and long-lived coherent oscillations of local observables. In this talk, I will present a unified understanding of these effects. Our analysis explains the phenomenology of real-time string dynamics investigated in a number of lattice gauge theories, as well as the anomalous dynamics observed in quantum Ising chains after quenches. Our findings establish confinement as a robust mechanism for hindering the approach to equilibrium in translationally-invariant quantum statistical systems with local interactions.
A Minimal Model of Kardar–Parisi–Zhang Physics
Speaker Žiga Krajnik
Abstract In recent years the observation of the Kardar–Parisi–Zhang universality class in spin-chain–like models, both quantum and classical, has aroused much interest. While a global non-Abelian symmetry seems necessary for Kardar–Parisi–Zhang scaling, a clarification of the role of integrability and a rigorous theoretical explanation are still pending. To this end, we introduce a classical integrable rotationally symmetric model of the Landau–Lifshitz type on the discrete space-time lattice, as a minimal model that exhibits all of the above requirements. Integrability of the model follows from an R-matrix that satisfies the set-theoretic Yang–Baxter equation. Interpreting the model as an integrable Trotterization of the lattice Landau–Lifshitz model we show numerically that it indeed exhibits Kardar–Parisi–Zhang scaling. Breaking integrability leads to a drift towards a diffusive dynamical exponent. A curious space-time self-duality of the model is demonstrated.
Integrable Floquet Hamiltonian for a Periodically Tilted 1D Gas
Speaker Andrea Colcelli
Abstract An integrable model subjected to a periodic driving gives rise generally to a nonintegrable Floquet Hamiltonian. In this talk I will show that the Floquet Hamiltonian of the integrable Lieb–Liniger model in the presence of a linear potential with a periodic time-dependent strength is instead integrable and its quasienergies can be determined using the Bethe ansatz approach. I will examine various aspects of the dynamics of the system at stroboscopic and intermediate times. Applications of this method to other models will be discussed as well.
Experimental observation of Luttinger liquid dynamics: relative Gaussification and memory effects
Speaker Spyros Sotiriadis
Abstract Quench dynamics in Gaussian models typically result in elimination of any non-Gaussian correlations that may be present in the initial state. Luttinger liquids are an exemption to this rule: due to the linear dispersion of the phonon modes, their dynamics remains coherent and preserves extensive memory of the initial state. I will present a detailed comparison between theoretical analysis and experimental data for a cold-atom realisation of Luttinger liquid dynamics. By systematic analysis of the role of external trap, finite size and nonlinear corrections in a realistic experimental system, we uncover a new mechanism for the emergence of Gaussian correlations valid for a sufficiently large class of initial states.
Entanglement Hamiltonians in 1D free lattice models after a global quantum quench
Speaker Giuseppe Di Giulio
Abstract We study the temporal evolution of the entanglement Hamiltonian of an interval after a global quantum quench in free lattice models in one spatial dimension, focussing in particular on critical evolution Hamiltonians. The temporal evolution of the gaps in the entanglement spectrum is also analysed. The entanglement Hamiltonians in these models are characterised by matrices that provide also contours for the entanglement entropies. The temporal evolution of the contour functions is studied, also by employing existing conformal field theory results for the semi-infinite line and the quasi-particle picture for the global quench.
Can we study the many-body localisation transition?
Speaker Scott Taylor
Abstract The many-body localised phase has received a great deal of attention from both theorists and experimentalists for over a decade; however, the nature of the transition between the ergodic and localised phases is still mysterious. I will present some results, based on complementary exact diagonalisation and tDMRG studies, that explore the length- and timescales required to observe thermalisation in the ergodic phase. Based on this I will discuss how the small system sizes and short times available to numerical and experimental studies limit what we can say about the nature and location of the transition.

Comments are closed.