arXiv subjects

Luciano Silvestri

Publications and source records attributed to Luciano Silvestri.

3 recordsLinked to original sources

arXiv2015

Fano-like anti-resonances in strongly coupled binary Coulomb systems

Molecular Dynamics (MD) simulations of a strongly coupled binary ionic mixture have revealed the appearance of sharp minima in the species resolved dynamical density fluctuation spectra. This phenomenon is reminiscent of the well-known Fano anti-resonance, occurring in various physical processes. We give a theoretical analysis using the Quasi Localized Charge Approximation, and demonstrate that the observed phenomenon in the equilibrium spectrum is a novel manifestation of the Fano mechanism, that occurs at characteristic frequencies of the system different from the conventional classical Fano frequencies.

physics.plasm-ph↗

arXiv2014

Typical, finite baths as a means of exact simulation of open quantum systems

There is presently considerable interest in accurately simulating the evolution of open systems for which Markovian master equations fail. Examples are systems that are time-dependent and/or strongly damped. A number of elegant methods have now been devised to do this, but all use a bath consisting of a continuum of harmonic oscillators. While this bath is clearly appropriate for, e.g., systems coupled to the EM field, it is not so clear that it is a good model for generic many-body systems. Here we explore a different approach to exactly simulating open-systems: using a finite bath chosen to have certain key properties of thermalizing many-body systems. To explore the numerical resources required by this method to approximate an open system coupled to an infinite bath, we simulate a weakly damped system and compare to the evolution given by the relevant Markovian master equation. We obtain the Markovian evolution with reasonable accuracy by using an additional averaging procedure, and elucidate how the typicality of the bath generates the correct thermal steady-state via the process of "eigenstate thermalization".

quant-ph↗

arXiv2011

The approach to typicality in many-body quantum systems

The recent discovery that for large Hilbert spaces, almost all (that is, typical) Hamiltonians have eigenstates that place small subsystems in thermal equilibrium, has shed much light on the origins of irreversibility and thermalization. Here we give numerical evidence that many-body lattice systems generically approach typicality as the number of subsystems is increased, and thus provide further support for the eigenstate thermalization hypothesis. Our results indicate that the deviation of many-body systems from typicality decreases exponentially with the number of systems. Further, by averaging over a number of randomly-selected nearest-neighbor interactions, we obtain a power-law for the atypicality as a function of the Hilbert space dimension, distinct from the power-law possessed by random Hamiltonians.

quant-ph↗