Linking localization effects on the dynamic behavior of many-spin systems with quantum irreversibility

F.S. LOZANO NEGRO, A. DALLALBA, A. ZWICK; GONZALO AGUSTIN ALVAREZ

Congreso; ICTP Summer School on Collective Behaviour in Quantum Matter; 2018

ICTP

The dynamics of complex quantum systems ubiquitous in condensed matter physics and in large molecules like proteins, is hard to be studied for understanding several observed non-intuitive effects. There are still many open questions, in particular, related to localization effects, non- thermalization and irreversibility of these dynamics.A new kind of phase transition has been observed in the coherent dynamical behavior of a 3D many-body quantum system [1]. It has been experimentally evidenced through quantum simulations using nuclear magnetic resonance (NMR) on a solid-state system [1-2]. A sudden quench on the interaction Hamiltonian dynamically induces correlations on the initially uncorrelated spins. The cluster-size of the correlated spins grows indefinitely as a function of time, and therefore, the spatial extension of the corresponding quantum superpositions that describes the states. Depending on the quench strength, a phase transition on the dynamical behavior is manifested leading to a localized dynamics for quench strengths lower than a critical value.In this work, we study the link between these dynamical localization effects and the possibility of time-reversing the spin dynamics by simulating the evolution of linear chain-spin systems under a perturbed double quantum hamiltonian and then refocusing the evolution by a non- perturbed double quantum hamiltonian. We analyze the echo obtained like a measure of the decoherence of the system and its dependence with the perturbation strength and the system?s size.[1] G. A. Álvarez, D. Suter, and R. Kaiser, Science 349, 846 (2015).[2] G. A. Álvarez and D. Suter, Phys. Rev. Lett. 104, 230403 (2010).