论文标题

综合哈密顿模拟的有效电路

Synthesizing efficient circuits for Hamiltonian simulation

论文作者

Mukhopadhyay, Priyanka, Wiebe, Nathan, Zhang, Hong Tao

论文摘要

我们提供了一种新的方法,用于汇编量子模拟电路,这些电路出现在Clifford和非克利福德操作中,可以将非克利福德操作的数量减少到最高$ 4 $。实际上,在许多情况下,大门总数减少了。我们表明,可以用最多$ m $(受控) - 旋转门实现通勤的通勤总和,其中$ m $是独特的非零特征值(忽略符号)的数量。因此,我们可以将相互通勤的哈密顿术语收集到满足这项工作中确定的几个对称性之一的组中,这些对称性允许对整个术语进行廉价模拟。我们进一步表明,在某些情况下可以通过将哈密顿术语部分分配给几个组来降低成本,并提供一种多项式时间经典算法,可以贪婪地将这些术语分配给适当的分组。我们进一步特别讨论了对费尔米金动力学情况的这些优化,并为我们的分组策略的QDRIFT提供了大量的数值模拟,以将我们的分组策略提高到6和4 Qubit Heisenberg型号,$ LIH $,$ H_2 $,并观察到1.8-3.2的非克利福德门的数量减少了1.8-3.2。这表明,基于猪肉的化学模拟在第二个量化中的模拟可能比以前认为的更实用。

We provide a new approach for compiling quantum simulation circuits that appear in Trotter, qDRIFT and multi-product formulas to Clifford and non-Clifford operations that can reduce the number of non-Clifford operations by a factor of up to $4$. In fact, the total number of gates reduce in many cases. We show that it is possible to implement an exponentiated sum of commuting Paulis with at most $m$ (controlled)-rotation gates, where $m$ is the number of distinct non-zero eigenvalues (ignoring sign). Thus we can collect mutually commuting Hamiltonian terms into groups that satisfy one of several symmetries identified in this work which allow an inexpensive simulation of the entire group of terms. We further show that the cost can in some cases be reduced by partially allocating Hamiltonian terms to several groups and provide a polynomial time classical algorithm that can greedily allocate the terms to appropriate groupings. We further specifically discuss these optimizations for the case of fermionic dynamics and provide extensive numerical simulations for qDRIFT of our grouping strategy to 6 and 4-qubit Heisenberg models, $LiH$, $H_2$ and observe a factor of 1.8-3.2 reduction in the number of non-Clifford gates. This suggests Trotter-based simulation of chemistry in second quantization may be even more practical than previously believed.

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