Berlin 2018 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 6: Dynamics in many-body systems: interference, equilibration and localization I (joint session DY/TT)
DY 6.9: Vortrag
Montag, 12. März 2018, 12:15–12:30, EB 107
Critical quench dynamics of random quantum spin chains — •Gergö Roosz1,2, Yu-Cheng Lin3, and Ferenc Igloi2 — 1Technische Universität Dresden — 2MTA Wigner RCP, Hungary — 3Graduate Institute of Applied Physics, National Chengchi University, Taipei, Taiwan
By means of free fermionic techniques combined with multiple precision arithmetic we study the time evolution of the average magnetization, m(t), of the random transverse-field Ising chain after global quenches. We observe different relaxation behaviors for quenches starting from different initial states to the critical point. Starting from a fully ordered initial state, the relaxation is logarithmically slow described by m(t) ∼ lna t, and in a finite sample of length L the average magnetization saturates at a size-dependent plateau mp(L) ∼ L−b; here the two exponents satisfy the relation b/a=ψ=1/2. Starting from a fully disordered initial state, the magnetization saturates to an asymptotic value mp(L) ∼ L−b′, with b′≈ 1.5. For both quenching protocols, finite-size scaling is satisfied in terms of the scaled variable lnt/Lψ. Furthermore, the distribution of long-time limiting values of the magnetization shows that the typical and the average values scale differently and the average is governed by rare events. The non-equilibrium dynamical behavior of the magnetization is explained through semi-classical theory.