Chemical simulation is a key application area that can leverage the power of quantum computers. A chemical simulator that implements a grid-based first quantization method has promising characteristics, but an implementation fully in quantum circuits seems to have not been published. Here, we present “crsQ” (chemical reaction simulator Q), which is a quantum circuit generator that generates such a chemical simulator. The generated simulator is capable of antisymmetrization of the initial wave function and time-evolution of the wave function based on the Suzuki–Trotter decomposition. The potential energy term of the Hamiltonian is implemented using arithmetic gates, such as adders, subtractors, multipliers, dividers, and square roots. Circuit diagrams and output samples are shown. The number of qubits in the circuits scales on the order of O(η log η), where η is the number of electrons. Each component of the generated circuit was verified in unit tests. Along with this development, we designed frameworks to ease the development of large-scale circuits, namely, a temporary qubit allocation framework and an abstract syntax tree framework for arithmetic formulas. These frameworks are expected to be useful in large-scale quantum circuit generators.

中文翻译：

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第一量子化量子计算机上的化学反应模拟器 （II）─基本处理：实现


化学模拟是可以利用量子计算机功能的关键应用领域。实现基于网格的第一次量子化方法的化学模拟器具有很有前途的特性，但完全在量子电路中的实现似乎尚未发布。在这里，我们介绍“crsQ”（化学反应模拟器 Q），它是一个量子电路发生器，可以生成这样的化学模拟器。生成的模拟器能够对初始波函数进行反对称化，并基于 Suzuki-Trotter 分解对波函数进行时间演化。哈密顿量的势能项是使用算术门实现的，例如加法器、减法器、乘数、除法器和平方根。显示了电路图和输出示例。电路中的量子比特数按 O（η log η） 的顺序缩放，其中 η 是电子数。生成的电路的每个组件都在单元测试中进行了验证。随着这一发展，我们设计了框架来简化大规模电路的开发，即临时量子比特分配框架和用于算术公式的抽象语法树框架。这些框架有望在大规模量子电路生成器中发挥作用。