Heat transport in the<i>X</i><i>X</i><i>Z</i>spin chain: from ballistic to diffusive regimes and dephasing enhancement

Abstract

In this work we study the heat transport in an XXZ spin-1/2 Heisenberg chain\nwith homogeneous magnetic field, incoherently driven out of equilibrium by\nreservoirs at the boundaries. We focus on the effect of bulk dephasing\n(energy-dissipative) processes in different parameter regimes of the system.\nThe non-equilibrium steady state of the chain is obtained by simulating its\nevolution under the corresponding Lindblad master equation, using the time\nevolving block decimation method. In the absence of dephasing, the heat\ntransport is ballistic for weak interactions, while being diffusive in the\nstrongly-interacting regime, as evidenced by the heat-current scaling with the\nsystem size. When bulk dephasing takes place in the system, diffusive transport\nis induced in the weakly-interacting regime, with the heat current\nmonotonically decreasing with the dephasing rate. In contrast, in the\nstrongly-interacting regime, the heat current can be significantly enhanced by\ndephasing for systems of small size.\n