paper

Asymptotic work statistics of periodically driven Ising chains

arXiv:1505.02924 · doi:10.1088/1742-5468/2015/08/P08030

Abstract

We study the work statistics of a periodically-driven integrable closed quantum system, addressing in particular the role played by the presence of a quantum critical point. Taking the example of a one-dimensional transverse Ising model in the presence of a spatially homogeneous but periodically time-varying transverse field of frequency , we arrive at the characteristic cumulant generating function , which is then used to calculate the work distribution function . By applying the Floquet theory we show that, in the infinite time limit, converges, starting from the initial ground state, towards an asymptotic steady state value whose small- behaviour depends only on the properties of the small-wave-vector modes and on a few important ingredients: the time-averaged value of the transverse field, , the initial transverse field, , and the equilibrium quantum critical point , which we find to generate a sequence of non-equilibrium critical points , with integer. When , we find a "universal" edge singularity in at a threshold value of which is entirely determined by . The form of that singularity --- Dirac delta derivative or square root --- depends on being or not at a non-equilibrium critical point . On the contrary, when , decays as a power-law for large , leading to different types of edge singularity at . Generalizing our calculations to the case in which we initialize the system in a finite temperature density matrix, the irreversible entropy generated by the periodic driving is also shown to reach a steady state value in the infinite time limit.

24 pages, 5 figures, published in Jour. Stat. Mech. Corrected error in the demonstration of appendix C

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