arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2003.05465quant-phcond-mat.str-el
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可解自旋模型的图不变量刻画

Characterization of solvable spin models via graph invariants

Adrian Chapman, Steven T. Flammia

摘要:

精确可解模型是物理学中必不可少的。对于自旋为1/2的多体系统,一类重要的模型包括那些可以映射到图上的自由费米子跳跃的模型。我们提供了一个完整的表征模型,可以解决这种方式。具体来说,我们减少了识别这种自旋模型的问题,图形理论的问题,识别线图,这已得到最佳解决。我们的结果的一个推论是一套完整的常数大小的对易结构,构成了一个自由费米子解决方案的障碍。我们发现,在这些模型中的对称性受到严格的约束。泡利对称对应于:(i)费米子跳跃图上的循环,(ii)费米子奇偶算符,或(iii)逻辑编码的量子比特。除了三个例外,这些对称扇区中的克利福德对称性必须是自由费米子模型本身的对称性。我们演示了如何从文献中的几个确切的自由费米子解决方案适合我们的形式主义,并给出了一个明确的例子,一个新的模型以前未知的自由费米子是可解的。

英文摘要:

Exactly solvable models are essential in physics. For many-body spin-1/2 systems, an important class of such models consists of those that can be mapped to free fermions hopping on a graph. We provide a complete characterization of models which can be solved this way. Specifically, we reduce the problem of recognizing such spin models to the graph-theoretic problem of recognizing line graphs, which has been solved optimally. A corollary of our result is a complete set of constant-sized commutation structures that constitute the obstructions to a free-fermion solution. We find that symmetries are tightly constrained in these models. Pauli symmetries correspond to either: (i) cycles on the fermion hopping graph, (ii) the fermion parity operator, or (iii) logically encoded qubits. Clifford symmetries within one of these symmetry sectors, with three exceptions, must be symmetries of the free-fermion model itself. We demonstrate how several exact free-fermion solutions from the literature fit into our formalism and give an explicit example of a new model previously unknown to be solvable by free fermions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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