20.500.12556/RUL-100087 Fisher information approach to nonequilibrium phase transitions in a quantum XXZ spin chain with boundary noise We investigated quantum critical behaviors in the nonequilibrium steady state of a XXZ spin chain with boundary Markovian noise using Fisher information. The latter represents the distance between two infinitesimally close states, and its superextensive size scaling witnesses a critical behavior due to a phase transition since all the interaction terms are extensive. Perturbatively, in the noise strength, we found superextensive Fisher information at anisotropy |Δ|⩽1 and irrational $\frac{\arccos\Delta}{\pi}$ irrespective of the order of two noncommuting limits, i.e., the thermodynamic limit and the limit of sending $\frac{\arccos\Delta}{\pi}$ to an irrational number via a sequence of rational approximants. From this result we argue the existence of a nonequilibrium quantum phase transition with a critical phase |Δ|⩽1. From the nonsuperextensivity of the Fisher information of reduced states, we infer that this nonequilibrium quantum phase transition does not have local order parameters but has nonlocal ones, at least at|Δ|=1. In the nonperturbative regime for the noise strength, we numerically computed the reduced Fisher information which lower bounds the full-state Fisher information and is superextensive only at |Δ|=1. From the latter result, we derived local order parameters at |Δ|=1 in the nonperturbative case. The existence of critical behavior witnessed by the Fisher information in the phase |Δ|<1 is still an open problem. The Fisher information also represents the best sensitivity for any estimation of the control parameter, in our case the anisotropy Δ, and its superextensivity implies enhanced estimation precision which is also highly robust in the presence of a critical phase. quantum mechanics spin models quantum chains phase transitions nonequilibrium statistical mechanics kvantna mehanika spinski modeli kvantne verige fazni prehodi neravnovesna statistična mehnaika true false false American Physical Society Angleški jezik Slovenski jezik American Physical Society Neznano 2018-03-05 09:55:30 2018-03-05 09:55:31 2022-08-24 17:16:43 0000-00-00 00:00:00 2017 0 0 Str. 104402-1-104402-10 iss. 10 Vol. 96 2017 0000-00-00 PostprintKoncna Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 530.145 2469-9950 10.1103/PhysRevB.96.104402 3179108 2997348 RAZ_Marzolino_Ugo_i2017.pdf RAZ_Marzolino_Ugo_i2017.pdf 1 E74552767CC91F042E2A30CCBA99D859 a48a6a419ac5751f7316da5e74157ccd7a6c305a5f28e50df7707f087d21155d 4bd48003-a1b5-11eb-a523-00155dcfd717 20.500.12556/rul/4bb65e8c-c241-4005-9c4d-fec99c0111a5 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=111588 https://journals.aps.org/prb/abstract/10.1103/PhysRevB.96.104402 1 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=109751 Fakulteta za matematiko in fiziko 0 0 0