Nonequilibrium Quantum Phase Transitions in the XY model: comparison of unitary time evolution and reduced density matrix approaches
| Autor: | Shigeru Ajisaka, Bojan Žunkovič, Felipe Barra |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: |
Physics
Quantum phase transition Phase transition Quantum Physics Statistical Mechanics (cond-mat.stat-mech) Condensed Matter - Mesoscale and Nanoscale Physics Time evolution General Physics and Astronomy FOS: Physical sciences Classical XY model Quantum mechanics Master equation Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Redfield equation Quantum mutual information Quantum Physics (quant-ph) Absolute zero Condensed Matter - Statistical Mechanics |
| Zdroj: | NEW JOURNAL OF PHYSICS Artículos CONICYT CONICYT Chile instacron:CONICYT |
| Popis: | We study nonequilibrium quantum phase transitions in XY spin 1/2 chain using the $C^*$ algebra. We show that the well-known quantum phase transition at magnetic field $h = 1$ persists also in the nonequilibrium setting as long as one of the reservoirs is set to absolute zero temperature. In addition, we find nonequilibrium phase transitions associated to imaginary part of the correlation matrix for any two different temperatures of the reservoirs at $h = 1$ and $h = h_{\rm c} \equiv|1-\gamma^2|$, where $\gamma$ is the anisotropy and $h$ the magnetic field strength. In particular, two nonequilibrium quantum phase transitions coexist at $h=1$. In addition we also study the quantum mutual information in all regimes and find a logarithmic correction of the area law in the nonequilibrium steady state independent of the system parameters. We use these nonequilibrium phase transitions to test the utility of two models of reduced density operator, namely Lindblad mesoreservoir and modified Redfield equation. We show that the nonequilibrium quantum phase transition at $h = 1$ related to the divergence of magnetic susceptibility is recovered in the mesoreservoir approach, whereas it is not recovered using the Redfield master equation formalism. However none of the reduced density operator approaches could recover all the transitions observed by the $C^*$ algebra. We also study thermalization properties of the mesoreservoir approach. Comment: 25 pages, 10 figures |
| Databáze: | OpenAIRE |
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