Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 44: Poster Session Correlated Electrons

TT 44.66: Poster

Thursday, March 17, 2011, 10:00–13:00, P1

Quantum relaxation in the XY chain with free boundaries — •Benjamin Blaß and Heiko Rieger — Theoretische Physik, Universität des Saarlandes, PF 151150, D-66041 Saarbrücken

We study the quantum relaxation in the spin-1/2 XY chain with free boundaries in a longitudinal field. The system is described by Ĥ=−J/2∑_i=1^L−1[1+γ/2σ̂_i^xσ̂_i+1^x+1−γ/2σ̂_i^yσ̂_i+1^y]−h/2∑_i=1^Lσ̂_i^z. By preparing the system in an eigenstate (e.g., the ground state) of the Hamiltonian for given parameters γ₀, J₀ and h₀ and then suddenly changing (i.e., quenching) the parameters to γ, J and h, the system evolves dynamically according to the Schrödinger equation into a stationary (i.e., time translational invariant) state, which is characterized by a length and time scale depending on the quench parameters. Due to the free boundaries, the local order parameter has a time and space dependent profile, which is computed. The issues of thermalization (or the lack thereof) as well as recurrence within a finite system are discussed.