Dresden 2011 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 28: CE: (General) Theory 2
TT 28.6: Talk
Tuesday, March 15, 2011, 15:15–15:30, HSZ 105
Thermalization of Interacting Fermions and Delocalization in Fock space — •Clemens Neuenhahn1 and Florian Marquardt1,2 — 1Institut für Theoretische Physik, Universität Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen, Germany — 2Max Planck Institut for the Science of Light, Günter-Scharoswky-Strasse 1/Bau 24,D-91058 Erlangen, Germany
By means of exact diagonalization, we investigate the onset of 'eigenstate thermalization' and the crossover to ergodicity in a system of 1D fermions with increasing interaction. We show that the fluctuations in the expectation values of the momentum distribution from eigenstate to eigenstate decrease with increasing coupling strength and system size. It turns out that these fluctuations are proportional to the inverse participation ratio of eigenstates represented in the Fock basis. The latter decays exponentially with increasing interaction strength before one enters the chaotic regime. We found good numerical evidence that in the thermodynamic limit eigenstate thermalization should set in even for vanishingly small perturbations.