Bruno Bertini "Transport in Closed Integrable Systems"

Thursday 7 Feb 2019, 15:00 → 16:00 Europe/Rome

248 (Ed. C primo piano )

I will consider a general framework for studying transport problems in closed quantum many-body systems. Two semi-infinite systems, initially held at different temperatures and chemical potentials, are suddenly joined and left to evolve unitarily. The focus is on the stationary flows of conserved charges persisting at infinite times after the junction. I will show that in integrable systems, a special class of systems characterised by an extensive number of local conservation laws, these flows are generically non-trivial. I will illustrate a new method to characterise them exactly in terms of a set of hydrodynamic equations. I will focus on the prototypical example of the XXZ spin-1/2 chain, where the results can be compared with high-precision numerical simulations based on matrix-product-state representations of the time-evolving state. I will show how the general hydrodynamic equations can account for the rich phenomenology observed when varying the parameters of the system, including the emergence of high-temperature sub-ballistic behaviours.