论文标题

递归变分量子汇编

Recursive Variational Quantum Compiling

论文作者

Bilek, Stian, Wold, Kristian

论文摘要

变性量子汇编(VQC)算法旨在用浅参数化的Ansatzes近似深量子电路,从而使它们更适合NISQ硬件。在本文中,提出了一个名为递归变分量子汇编(RVQC)算法的VQC的变体。现有的VQC算法通常需要在编译过程中连贯执行全电路。在噪声的影响下,足够深的目标电路使使用普通VQC的编译使得不可行。由于通常使用基于梯度的量子古典方法来完成编译,因此量子噪声在优化过程中表现为嘈杂的梯度,因此很难获得收敛。另一方面,RVQC可以首先将电路分为$ n $短的子电路来编译电路,然后一次评估一个子电路。结果,实现RVQC所需的电路深度不取决于目标电路的深度,而是取决于子电路的深度。选择足够高的$ n $,因此可以确保足够浅的子电路,可以单独编译。我们展示了此属性的数学证据。在IBM Santiago设备的噪声模型上将RVQC与VQC进行了比较,目的是编译几个随机生成的五分位电路,该电路大约为1000。这表明VQC无法在500次迭代中收敛。另一方面,在将目标电路分为$ n = 5 $零件时,RVQC能够在总共500次迭代范围内收敛到$ 0.90 \ pm 0.05 $。我们认为这是由于缓解噪声引起的贫瘠高原的结果。

Variational quantum compiling (VQC) algorithms aim to approximate deep quantum circuits with shallow parameterized ansatzes, making them more suitable for NISQ hardware. In this article a variant of VQC named the recursive variational quantum compiling (RVQC) algorithm is proposed. Existing VQC algorithms typically require coherently executing the full circuit during compilation. Under the influence of noise, sufficiently deep target circuits make compiling unfeasible using ordinary VQC. Since the compiling is often accomplished using a gradient-based quantum-classical approach, the quantum noise manifest as a noisy gradient during optimization, making convergence hard to obtain. On the other hand, RVQC can compile a circuit by first dividing it into $N$ shorter sub-circuits, then evaluate one sub-circuit at a time. As a result, the circuit depth required to implement RVQC is not dependent on the depth of the target circuit, but on the depth of the sub-circuits. Choosing a high enough $N$ thus ensures sufficiently shallow sub-circuit which can be successfully compiled individually. We show mathematical evidence of this property. RVQC was compared with VQC on a noise model of the IBM Santiago device with the goal of compiling several randomly generated five-qubit circuits of approximately depth 1000. It was shown that VQC was not able to converge within 500 iterations of optimization. On the other hand, RVQC was able to converge to a fidelity of $0.90 \pm 0.05$ within a total of 500 iterations when splitting the target circuits into $N = 5$ parts. We argue that this comes as a result of the mitigation of noise-induced barren plateaus.

扫码加入交流群

加入微信交流群

微信交流群二维码

扫码加入学术交流群,获取更多资源