TY - JOUR
T1 - Dynamical quantum correlations of Ising models on an arbitrary lattice and their resilience to decoherence
JF - New Journal of Physics
Y1 - 2013
A1 - Michael Foss-Feig
A1 - Kaden R A Hazzard
A1 - John J Bollinger
A1 - Ana Maria Rey
A1 - Charles W Clark
AB - Ising models, and the physical systems described by them, play a central role in generating entangled states for use in quantum metrology and quantum information. In particular, ultracold atomic gases, trapped ion systems, and Rydberg atoms realize long-ranged Ising models, which even in the absence of a transverse field can give rise to highly non-classical dynamics and long-range quantum correlations. In the first part of this paper, we present a detailed theoretical framework for studying the dynamics of such systems driven (at time t=0) into arbitrary unentangled non-equilibrium states, thus greatly extending and unifying the work of Ref. [1]. Specifically, we derive exact expressions for closed-time-path ordered correlation functions, and use these to study experimentally relevant observables, e.g. Bloch vector and spin-squeezing dynamics. In the second part, these correlation functions are then used to derive closed-form expressions for the dynamics of arbitrary spin-spin correlation functions in the presence of both T_1 (spontaneous spin relaxation/excitation) and T_2 (dephasing) type decoherence processes. Even though the decoherence is local, our solution reveals that the competition between Ising dynamics and T_1 decoherence gives rise to an emergent non-local dephasing effect, thereby drastically amplifying the degradation of quantum correlations. In addition to identifying the mechanism of this deleterious effect, our solution points toward a scheme to eliminate it via measurement-based coherent feedback.
VL - 15
U4 - 113008
UR - http://arxiv.org/abs/1306.0172v1
CP - 11
J1 - New J. Phys.
U5 - 10.1088/1367-2630/15/11/113008
ER -