SIAM Journal on Computing, Volume 49, Issue 6, Page 1332-1362, January 2020.
We examine the problem of determining whether a multiqubit two-local Hamiltonian can be made stoquastic by single-qubit unitary transformations. We prove that when such a Hamiltonian contains one-local terms, then this task can be NP-hard. This is shown by constructing a class of Hamiltonians for which performing this task is equivalent to deciding 3-SAT. In contrast, we show that when such a Hamiltonian contains no one-local terms then this task is easy; namely, we present an algorithm which decides, in a number of arithmetic operations over $\mathbb{R}$ which is polynomial in the number of qubits, whether the sign problem of the Hamiltonian can be cured by single-qubit rotations.

中文翻译：

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两局部Qubit哈密顿量的硬度和易于治愈的符号问题

SIAM计算杂志，第49卷，第6期，第1332-1362页，2020年1月。
我们研究了确定单量子位unit变换是否可以使多量子位两局部哈密顿量成为随机问题。我们证明，当这样的哈密顿量包含一个局部项时，则此任务可能是NP难的。这是通过构造一类哈密顿量来表明的，对其执行此任务等同于确定3-SAT。相反，我们表明，当这样的哈密顿量不包含一个局部项时，此任务就很容易了。即，我们提出一种算法，该算法在超过$ \ mathbb {R} $的多个算术运算中确定量子位的数量是多项式，该算法是否可以通过单量子位旋转来解决哈密顿量的正负号问题。