@article{ZunkovicProsen2010, author = {Zunkovic, Bojan and Prosen, Tomaz}, title = {Explicit solution of the Lindblad equation for nearly isotropic boundary driven XY spin 1/2 chain}, issn = {1742-5468}, doi = {10.1088/1742-5468/2010/08/P08016}, year = {2010}, abstract = {Explicit solution for the two-point correlation function in a non-equilibrium steady state of a nearly isotropic boundary driven open XY spin 1/2 chain in the Lindblad formulation is provided. A non-equilibrium quantum phase transition from exponentially decaying correlations to long range order is discussed analytically. In the regime of long range order a new phenomenon of correlation resonances is reported, where the correlation response of the system is unusually high for certain discrete values of the external bulk parameter, e.g. the magnetic field.}, language = {en} } @article{ProsenIlievski2011, author = {Prosen, Tomaz and Ilievski, Enej}, title = {Nonequilibrium phase transition in a periodically driven XY spin chain}, series = {Physical review letters}, volume = {107}, journal = {Physical review letters}, number = {6}, publisher = {American Physical Society}, address = {College Park}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.107.060403}, pages = {4}, year = {2011}, abstract = {We present a general formulation of Floquet states of periodically time-dependent open Markovian quasifree fermionic many-body systems in terms of a discrete Lyapunov equation. Illustrating the technique, we analyze periodically kicked XY spin-1/2 chain which is coupled to a pair of Lindblad reservoirs at its ends. A complex phase diagram is reported with reentrant phases of long range and exponentially decaying spin-spin correlations as some of the system's parameters are varied. The structure of phase diagram is reproduced in terms of counting nontrivial stationary points of Floquet quasiparticle dispersion relation.}, language = {en} } @article{Prosen2011, author = {Prosen, Tomaz}, title = {Complexity and nonseparability of classical Liouvillian dynamics}, series = {Physical review : E, Statistical, nonlinear and soft matter physics}, volume = {83}, journal = {Physical review : E, Statistical, nonlinear and soft matter physics}, number = {3}, publisher = {American Physical Society}, address = {College Park}, issn = {1539-3755}, doi = {10.1103/PhysRevE.83.031124}, pages = {5}, year = {2011}, abstract = {We propose a simple complexity indicator of classical Liouvillian dynamics, namely the separability entropy, which determines the logarithm of an effective number of terms in a Schmidt decomposition of phase space density with respect to an arbitrary fixed product basis. We show that linear growth of separability entropy provides a stricter criterion of complexity than Kolmogorov-Sinai entropy, namely it requires that the dynamics be exponentially unstable, nonlinear, and non-Markovian.}, language = {en} }