Department of Physics, FMF, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia.
Phys Rev Lett. 2011 May 27;106(21):217206. doi: 10.1103/PhysRevLett.106.217206.
An explicit matrix product ansatz is presented, in the first two orders in the (weak) coupling parameter, for the nonequilibrium steady state of the homogeneous, nearest neighbor Heisenberg XXZ spin 1/2 chain driven by Lindblad operators which act only at the edges of the chain. The first order of the density operator becomes, in the thermodynamic limit, an exact pseudolocal conservation law and yields-via the Mazur inequality-a rigorous lower bound on the high-temperature spin Drude weight. Such a Mazur bound is a nonvanishing fractal function of the anisotropy parameter Δ for |Δ|<1.
本文提出了一种显式矩阵乘积算符，在（弱）耦合参数的前两阶，用于由仅在链边缘作用的林德布拉德算符驱动的均匀近邻海森堡 XXZ 自旋 1/2 链的非平衡定态。在热力学极限下，密度算符的一阶成为一个精确的拟局域守恒律，并通过马祖尔不等式给出高温自旋德拜质量的严格下界。对于 |Δ|<1，这样的马祖尔界是各向异性参数 Δ 的非平凡分形函数。
