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arXiv 2008.09854quant-ph
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哈密顿对角化的变分量子算法

A variational quantum algorithm for Hamiltonian diagonalization

Jinfeng Zeng, Chenfeng Cao, Chao Zhang, Pengxiang Xu, Bei Zeng

摘要:

哈密顿对角化是理解量子系统的物理性质和实际应用的核心。设计能够加速哈密顿对角化的量子算法,特别是那些能够在近期量子器件上实现的量子算法,是非常有必要的。在这项工作中,我们提出了一个变分算法的哈密顿对角化(VQHD)的量子系统,探讨了重要的物理性质,如温度,局域性和相关性,系统。其核心思想是系统的热态编码了系统哈密顿量的本征值和本征态信息。为了得到哈密顿量的全谱,我们使用了一种高温下的量子虚时间演化算法,它制备了一个具有小关联长度的热态。有了Trotterization,这就允许我们通过仅在少数站点上的局部酉变换来实现虚时间演化的每一步。对角化这些热状态,从而导致一个完整的知识的哈密顿本征系统。我们应用我们的算法对角化局部汉密尔顿并返回高精度的结果。我们的VQHD算法为近期量子计算机的应用提供了新的思路。

英文摘要:

Hamiltonian diagonalization is at the heart of understanding physical properties and practical applications of quantum systems. It is highly desired to design quantum algorithms that can speedup Hamiltonian diagonalization, especially those can be implemented on near-term quantum devices. In this work, we propose a variational algorithm for Hamiltonians diagonalization (VQHD) of quantum systems, which explores the important physical properties, such as temperature, locality and correlation, of the system. The key idea is that the thermal states of the system encode the information of eigenvalues and eigenstates of the system Hamiltonian. To obtain the full spectrum of the Hamiltonian, we use a quantum imaginary time evolution algorithm with high temperature, which prepares a thermal state with a small correlation length. With Trotterization, this then allows us to implement each step of imaginary time evolution by a local unitary transformation on only a small number of sites. Diagonalizing these thermal states hence leads to a full knowledge of the Hamiltonian eigensystem. We apply our algorithm to diagonalize local Hamiltonians and return results with high precision. Our VQHD algorithm sheds new light on the applications of near-term quantum computers.

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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