论文标题
通过随机电路采样的量子至上的边界
Boundaries of quantum supremacy via random circuit sampling
论文作者
论文摘要
Google最近的量子至上实验预示了一个过渡点，量子计算执行了计算任务，随机电路采样，这超出了现代超级计算机的实际影响范围。我们检查了外推到具有较大量子数和门的电路中观察到的量子运行时优势的约束。由于量子和门的数量的实验保真度呈指数下降，我们证明了当前的忠诚度比几百个门更深的电路的理论经典运行时优势，而跨透明镜基准的量子运行时间将量子优势的区域限制为几百Qubits。但是，量子运行时优势边界在电路宽度和深度方面相对于降低的错误率呈指数增长，我们的工作突出了沿该线路持续进步的重要性。测得的错误率的外推表明，可以实现跨膜片基准测试中计算可行的量子运行时优势的限制电路大小，这与对早期实现表面代码和其他量子误差校正方法的预期相吻合。因此，通过随机电路采样的量子至高无上的边界可能与近期误差校正量子计算的出现偶然地重合。
Google's recent quantum supremacy experiment heralded a transition point where quantum computing performed a computational task, random circuit sampling, that is beyond the practical reach of modern supercomputers. We examine the constraints of the observed quantum runtime advantage in an extrapolation to circuits with a larger number of qubits and gates. Due to the exponential decrease of the experimental fidelity with the number of qubits and gates, we demonstrate for current fidelities a theoretical classical runtime advantage for circuits deeper than a few hundred gates, while quantum runtimes for cross-entropy benchmarking limit the region of a quantum advantage to a few hundred qubits. However, the quantum runtime advantage boundary in circuit width and depth grows exponentially with respect to reduced error rates, and our work highlights the importance of continued progress along this line. Extrapolations of measured error rates suggest that the limiting circuit size for which a computationally feasible quantum runtime advantage in cross-entropy benchmarking can be achieved approximately coincides with expectations for early implementations of the surface code and other quantum error correction methods. Thus the boundaries of quantum supremacy via random circuit sampling may fortuitously coincide with the advent of scalable, error corrected quantum computing in the near term.
