Wang Hai Tao, Cho Sam Young
Postdoctoral Research Station of Material Science and Engineering, Chongqing University, Chongqing 400044,The People's Republic of China. Centre for Modern Physics and Department of Physics, Chongqing University, Chongqing 400044, The People's Republic of China.
J Phys Condens Matter. 2015 Jan 14;27(1):015603. doi: 10.1088/0953-8984/27/1/015603. Epub 2014 Dec 5.
In order to investigate the quantum phase transition in the one-dimensional quantum compass model, we numerically calculate non-local string correlations, entanglement entropy and fidelity per lattice site by using the infinite matrix product state representation with the infinite time evolving block decimation method. In the whole range of the interaction parameters, we find that four distinct string orders characterize the four different Haldane phases and the topological quantum phase transition occurs between the Haldane phases. The critical exponents of the string order parameters β = 1/8 and the cental charges c = 1/2 at the critical points show that the topological phase transitions between the phases belong to an Ising type of universality classes. In addition to the string order parameters, the singularities of the second derivative of the ground state energies per site, the continuous and singular behaviors of the Von Neumann entropy and the pinch points of the fidelity per lattice site manifest that the phase transitions between the phases are of the second-order, in contrast to the first-order transition suggested in previous studies.
为了研究一维量子罗盘模型中的量子相变，我们采用无限时间演化块抽取方法结合无限矩阵乘积态表示，对每个格点的非局域弦关联、纠缠熵和保真度进行了数值计算。在相互作用参数的整个范围内，我们发现四种不同的弦序表征了四个不同的霍尔丹相，并且在霍尔丹相之间发生了拓扑量子相变。临界点处弦序参数的临界指数β = 1/8以及中心荷c = 1/2表明，这些相之间的拓扑相变属于伊辛型普适类。除了弦序参数外，每个格点基态能量二阶导数的奇点、冯·诺依曼熵的连续和奇异行为以及每个格点保真度的尖点都表明，这些相之间的相变是二阶的，这与先前研究中提出的一阶相变形成对比。
