论文标题
改善标志问题:绝热量子蒙特卡洛
An Amelioration for the Sign Problem: Adiabatic Quantum Monte Carlo
论文作者
论文摘要
我们介绍了绝热量子蒙特卡洛(AQMC)方法,在其中逐渐提高相互作用强度,作为符号问题的改善。它是由绝热定理的动机,如果演变时间足够长,将接近真正的地面。我们证明AQMC呈指数增强的平均符号,以便可以访问足够低的温度并探测地面态性能。这是一个受控的近似值,满足变异定理,并为地面能量提供上限。我们首先基于AQMC与正方形晶格上未掺杂的哈伯德模型进行基准测试,该模型已知在传统的量子蒙特卡洛形式主义中无标志性问题。接下来,我们针对掺杂的四腿梯子哈伯德模型的密度 - 矩阵 - 肾脏固定组方法测试AQMC,并证明了其出色的准确性。作为一个非平凡的示例,我们将我们的方法应用于Hubbard Model,以$ p = 1/8 $掺杂$ 16 \ times 8 $系统,并讨论其基础属性。我们最终利用了我们的方法,并证明了$ u(1)_2 \ sim su(2)_1 $拓扑顺序的出现在密切相关的Chern绝缘子中。
We introduce the adiabatic quantum Monte Carlo (AQMC) method, where we gradually crank up the interaction strength, as an amelioration of the sign problem. It is motivated by the adiabatic theorem and will approach the true ground-state if the evolution time is long enough. We demonstrate that the AQMC enhances the average sign exponentially such that low enough temperatures can be accessed and ground-state properties probed. It is a controlled approximation that satisfies the variational theorem and provides an upper bound for the ground-state energy. We first benchmark the AQMC vis-à-vis the undoped Hubbard model on the square lattice which is known to be sign-problem-free within the conventional quantum Monte Carlo formalism. Next, we test the AQMC against the density-matrix-renormalization-group approach for the doped four-leg ladder Hubbard model and demonstrate its remarkable accuracy. As a nontrivial example, we apply our method to the Hubbard model at $p=1/8$ doping for a $16\times 8$ system and discuss its ground-state properties. We finally utilize our method and demonstrate the emergence of $U(1)_2\sim SU(2)_1$ topological order in a strongly correlated Chern insulator.