Department of Physics, Faculty of Mathematics, University of Ljubljana, 1000 Ljubljana, Slovenia.
Phys Rev Lett. 2013 Feb 15;110(7):070602. doi: 10.1103/PhysRevLett.110.070602. Epub 2013 Feb 12.
We show that in a nonintegrable spin ladder system with the XX type of coupling along the legs and the XXZ type along the rungs there are invariant subspaces that support ballistic magnetization transport. In the complementary subspace the transport is found to be diffusive. This shows that (i) quantum chaotic systems can possess ballistic subspaces, and (ii) diffusive and ballistic transport modes can coexist in a rather simple nonintegrable model. In the limit of an infinite anisotropy in rungs the system studied is equivalent to the one-dimensional Hubbard model.
我们表明，在具有沿腿的 XX 型耦合和沿梯级的 XXZ 型耦合的非可积自旋梯级系统中，存在支持弹道磁化传输的不变子空间。在互补子空间中，发现传输是扩散的。这表明 (i) 量子混沌系统可以具有弹道子空间，以及 (ii) 扩散和弹道传输模式可以在相当简单的非可积模型中共存。在梯级各向异性无穷大的极限下，所研究的系统等同于一维 Hubbard 模型。
