美国IBM quantum公司 Youngseok Kim、Abhinav Kandala研究团队取得一项新突破。他们的研究认为可扩展的噪声量子电路误差抑制产生竞争的期望值。2023年2月6日，国际知名学术期刊《自然—物理学》发表了这一成果。
课题组展示了零噪声外推在实际相关量子电路中的效用，使用多达26个量子比特，电路深度为120和1080个CNOT门。研究人员研究了乘积态和增加尺寸的量子纠缠Clifford回路等典型例子的标度方法，并将其推广到模拟具有不同耦合的二维Ising自旋晶格的淬灭动力学。这些实验表明，在误差缓解后，物理相关观测值的准确性大大超过了先前的预期值。
此外，研究人员还表明，通过额外的错误抑制技术和减少电路时间的本机门分解，误差缓解的效果大大增强。通过结合这些方法，其量子模拟的准确性超过了从建立张量网络方法获得的经典近似。这些结果建立了有噪声的数字量子处理器的量子优势潜力。
据悉，现有量子处理器中的噪声只能使其近似于理想的量子计算。然而，对于期望值的计算，这些近似可以通过减少误差来改进。这已经在小型系统中得到了实验证明，但这些方法在更大的电路体积上的缩放仍然未知。
附：英文原文
Title: Scalable error mitigation for noisy quantum circuits produces competitive expectation values
Author: Kim, Youngseok, Wood, Christopher J., Yoder, Theodore J., Merkel, Seth T., Gambetta, Jay M., Temme, Kristan, Kandala, Abhinav
Issue&Volume: 2023-02-06
Abstract: Noise in existing quantum processors only enables an approximation to ideal quantum computation. However, for the computation of expectation values, these approximations can be improved by error mitigation. This has been experimentally demonstrated in small systems but the scaling of these methods to larger circuit volumes remains unknown. Here we demonstrate the utility of zero-noise extrapolation for practically relevant quantum circuits using up to 26qubits, circuit depths of 120 and 1,080CNOT gates. We study the scaling of the method for canonical examples of product states and entangling Clifford circuits of increasing size, and extend it to simulating the quench dynamics of two-dimensional Ising spin lattices with varying couplings. These experiments reveal that the accuracy of physically relevant observables after error mitigation substantially exceeds previously expected values. Furthermore, we show that the efficacy of error mitigation is greatly enhanced by additional error suppression techniques and native gate decomposition that reduce the circuit time. By combining these methods, the accuracy of our quantum simulation surpasses the classical approximations obtained from an established tensor network method. These results establish the potential of a useful quantum advantage using noisy, digital quantum processors.
DOI: 10.1038/s41567-022-01914-3
Source: https://www.nature.com/articles/s41567-022-01914-3