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Non-zero entropy density in the XY chain out of equilibrium

Walter H. Aschbacher
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Abstract

The von Neumann entropy density of a block of n spins is proved to be non-zero for large n in the non-equilibrium steady state of the XY chain constructed by coupling a finite cutout of the chain to the two infinite parts to its left and right which act as thermal reservoirs at different temperatures. Moreover, the non-equilibrium density is shown to be strictly greater than the density in thermal equilibrium.

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Walter H. Aschbacher. 2006-10-20. Non-zero entropy density in the XY chain out of equilibrium. https://doi.org/10.1007/s11005-006-0115-1

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