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

ANALIA ZWICK; FABRICIO LOZANO; GONZALO A. ALVAREZ; AGUSTIN DALL'ALBA

Congreso; XXI Giambiagi Winter School Quantum simulations and quantum metrology with cold trapped ions; 2019

XXI Giambiagi Winter School Quantum simulations and quantum metrology with cold trapped ions

.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 stillmany 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 magneticresonance (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 afunction 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 leadingto 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 quantumhamiltonian 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 strengthand the system?s size.