Current advancements in technology have focused the attention of the quantum computing community toward exploring the potential of near-term devices whose computing power surpasses that of classical computers in practical applications. An unresolved central question revolves around whether the inherent noise in these devices can be overcome or whether any potential quantum advantage would be limited. There is no doubt that crosstalk is one of the main sources of noise in noisy intermediate-scale quantum (NISQ) systems, and it poses a fundamental challenge to hardware designs. Crosstalk between parallel instructions can corrupt quantum states and cause incorrect program execution. In this study, we present a necessary analysis of the crosstalk error effect on NISQ devices. Our approach is extremely straightforward and practical to estimate the crosstalk error of various multi-qubit devices. In particular, we combine the randomized benchmarking (RB) and simultaneous randomized benchmarking (SRB) protocol to estimate the crosstalk error from the correlation controlled-NOT (CNOT) gate. We demonstrate this protocol experimentally on 5-, 7-, \& 16-qubit devices. Our results demonstrate the crosstalk error model of three different IBM quantum devices over the experimental week and compare the error variation against the machine, number of qubits, quantum volume, processor, and topology. We then confirm the improvement in the circuit fidelity on different benchmarks by up to 3.06x via inserting an instruction barrier, as compared with an IBM quantum noisy device which offers near-optimal crosstalk mitigation in practice. Finally, we discuss the current system limitation, its tradeoff on fidelity and depth, noise beyond the NISQ system, and mitigation opportunities to ensure that the quantum operation can perform its quantum magic undisturbed.

翻译：当前技术的进步已将量子计算界的注意力聚焦于探索近期待器件的潜力，这些器件在实际应用中的计算能力超越了经典计算机。一个悬而未决的核心问题在于：这些器件固有的噪声是否可以被克服，或者任何潜在的量子优势是否会受到限制。毫无疑问，串扰是噪声中等规模量子（NISQ）系统中噪声的主要来源之一，且对硬件设计构成了根本性挑战。并行指令之间的串扰可能破坏量子态，导致程序执行错误。在本研究中，我们针对NISQ器件上串扰误差的影响进行了必要分析。我们的方法极其直接且实用，能够估算各种多量子比特器件的串扰误差。具体而言，我们结合了随机基准测试（RB）和同步随机基准测试（SRB）协议，通过关联受控非门（CNOT）来估算串扰误差。我们在5量子比特、7量子比特和16量子比特器件上实验验证了这一协议。我们的结果展示了三种不同IBM量子器件在一周实验内的串扰误差模型，并比较了误差随机器类型、量子比特数量、量子体积、处理器及拓扑结构的变化。随后，我们确认通过插入指令屏障，电路保真度在不同基准测试上提升了高达3.06倍，与提供近乎最优串扰抑制的IBM量子噪声器件相比表现更优。最后，我们讨论了当前系统的局限性、保真度与深度之间的权衡、超越NISQ系统的噪声问题，以及确保量子操作不受干扰地发挥其量子魔力的抑制机会。