发表机构
Duke Quantum Center, Duke University; Department of Electrical and Computer Engineering, Duke University; University of Southern California; Center for Quantum Information Science and Technology, University of Southern California; Department of Physics, Duke University; Department of Chemistry, Duke University（杜克大学量子中心; 杜克大学电气与计算机工程系; 南加州大学; 南加州大学量子信息技术中心; 杜克大学物理系; 杜克大学化学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究人员提出基于重叠的电路级基准EPCL，通过测量双不相交量子寄存器输出态重叠随电路深度的变化，实现无需理想输出经典模拟的大规模量子系统聚合性能测量。
AI 中文摘要
量子基准提供了紧凑的性能度量，这对评估和比较量子系统至关重要。电路级基准尤其有价值，因为它们能捕捉相互作用操作产生的噪声累积效应，但现有方法可能需要结构化门集、代价高昂的编译、参考输出的经典模拟，或无法捕捉全寄存器行为的子系统分解。我们提出了基于重叠的电路级基准——每电路层误差（Error Per Circuit Layer, EPCL），该方法通过将相同的随机电路应用于两个不相交的量子寄存器，并测量它们输出态之间的重叠随电路深度的变化，来估计有效层极化。EPCL避免了理想输出分布的经典模拟和对已知参考态的恢复，且与任意门集兼容，包括非Clifford门。我们推导了系综平均退极化模型下的预期重叠衰减，并确定了拟合衰减参数代表有效层极化的假设条件。数值模拟表明，EPCL在弱局域随机噪声下可恢复预测的极化，在更强的随机噪声水平下仍可由单指数衰减良好描述。模拟还进一步显示，与固定纠缠层相关的相干误差可能需要Pauli扭转或随机编译来产生预期的衰减，而寄存器间的相关性会对测量到的重叠贡献额外的协方差项。最后，在IBM量子硬件上开展的实验证明，8量子比特和16量子比特实现中存在清晰的EPCL衰减。这些结果支持EPCL作为一种测量聚合寄存器性能的方法，无需理想电路输出的经典模拟或限制为结构化门集。
英文摘要
Quantum benchmarks provide compact measures of performance that are important for evaluating and comparing quantum systems. Circuit-level benchmarks are particularly valuable because they capture the accumulated effects of noise across interacting operations, but existing approaches may require structured gate sets and costly compilation, classical simulation of reference outputs, or subsystem decompositions that do not capture full-register behavior. We introduce Error Per Circuit Layer (EPCL), an overlap-based circuit-level benchmark that estimates an effective layer polarization by applying identical random circuits to two disjoint quantum registers and measuring the overlap between their output states as a function of circuit depth. EPCL avoids classical simulation of ideal output distributions and recovery to a known reference state, and is compatible with arbitrary gate sets, including non-Clifford gates. We derive the expected overlap decay under an ensemble-averaged depolarizing model and identify the assumptions under which the fitted decay parameter represents an effective layer polarization. Numerical simulations show that EPCL recovers the predicted polarization under weak local stochastic noise and remains well described by a single-exponential decay at stronger stochastic noise levels. The simulations further show that coherent errors associated with fixed entangling layers may require Pauli twirling or randomized compiling to produce the expected decay, while inter-register correlations contribute an additional covariance term to the measured overlap. Finally, experiments on IBM quantum hardware demonstrate clear EPCL decay in 8- and 16-qubit implementations. These results support EPCL as a method for measuring aggregate register performance without requiring classical simulation of ideal circuit outputs or restriction to structured gate sets.
