Extended cluster algorithm in quantum simulations - art. no. 020406

We propose an extension of the quantum cluster algorithm by a combined use of the Fortuin-Kasteleyn mapping and the Hubbard-Stratonovich transformatio n. To describe the idea, we consider the S = 1/2 XXZ chain model and expres s the partition function as the sum in an extended configuration space of s pins, graphs, and fields. Then it is clarified that this algorithm possesse s a computationally tractable continuous-time limit and maintains virtues o f the quantum cluster algorithm. Numerical simulations are performed and it s applicability is demonstrated. Further, we discuss potential gains in our algorithm.