Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 19: Correlated Electrons: Nonequilibrium Quantum Many-Body Systems 2 (jointly with DY)

TT 19.10: Vortrag

Montag, 16. März 2015, 17:30–17:45, H 3010

Statistical properties of all eigenstates in isolated quantum systems — •Wouter Beugeling, Alexei Andreanov, Roderich Moessner, and Masud Haque — Max-Planck-Institut für Physik komplexer Systeme (MPIPKS), Dresden, Germany

Traditionally, the focus of research in quantum many-body systems has been the ground state and low-lying excited states. For isolated quantum systems, however, the complete spectrum is relevant, because a mechanism that lets the system equilibrate to low energy is absent. The eigenstates in the bulk of the spectrum have significantly different properties than those at the edge, which shows for instance in the entanglement entropy, which typically follows a volume law in the bulk and an area law at the edge.

In this talk, I will discuss the typical behaviour of entanglement entropy and participation ratios of eigenstates as a function of location in the spectrum. Motivated by the similar behaviour of high values in the bulk and low values at the edge, and by the interpretation of both as measures of randomness in the eigenstates, we quantitatively analyse the correlation between the two quantities. We connect their behaviour to that of diagonal and off-diagonal matrix elements of local observables. To this end, we study the dependence on system size and on the amount of integrability breaking, which we introduce by looking at tunable Hamiltonians.