We present a framework for quantum process tomography of two-ion interactions that leverages modulations of the trapping potential and composite pulses from a global laser beam to achieve individual-ion addressing. Tomographic analysis of identity and delay processes reveals dominant error contributions from laser decoherence and slow qubit frequency drift during the tomography experiment. We use this framework on two co-trapped ⁴⁰Ca⁺ ions to analyze both an optimized and an overpowered Mlmer–Srensen gate and to compare the results of this analysis to a less informative Bell-state tomography measurement and to predictions based on a simplified noise model. These results show that the technique is effective for the characterization of two-ion quantum processes and for the extraction of meaningful information about the errors present in the system. The experimental convenience of this method will allow for more widespread use of process tomography for characterizing entangling gates in trapped-ion systems.

我们提出了一个用于双离子相互作用的量子过程断层扫描的框架，该框架利用来自全局激光束的捕获电位和复合脉冲的调制来实现单个离子寻址。身份和延迟过程的断层扫描分析揭示了断层扫描实验期间激光退相干和慢量子位频率漂移的主要误差贡献。我们在两个共同捕获的⁴⁰ Ca ⁺上使用这个框架离子来分析优化的和超功率的 Mlmer-Srensen 门，并将该分析的结果与信息较少的贝尔状态断层扫描测量和基于简化噪声模型的预测进行比较。这些结果表明，该技术对于表征双离子量子过程和提取有关系统中存在的错误的有意义的信息是有效的。这种方法的实验便利性将允许更广泛地使用过程断层扫描来表征俘获离子系统中的纠缠门。