论文标题
最佳量子层析成像和嘈杂的大门
Optimal Quantum State Tomography with Noisy Gates
论文作者
论文摘要
量子状态断层扫描(QST)代表了量子处理器表征,验证和验证(QCVV)的重要工具。仅对于少数理想化的方案,QST的最佳测量设置有分析结果。例如,在非分类测量值的设置中,QST的最佳最小测量算子集具有相互无偏见的本本基碱。但是,在其他设置中,取决于投影运算符的等级和量子系统的大小,需要在数值上近似地测量的最佳测量值。我们通过引入自定义有效QST的框架来概括这个问题。在这里,我们扩展了自定义的QST,并在测量过程中应用的一些量子门嘈杂的情况下,寻找QST的最佳测量集。为了实现这一目标,我们使用两个不同的噪声模型:首先,去极化通道,以及单Qubit和两个Quibit大门的第二,过度和不足的旋转(有关更多信息,请参阅方法)。我们通过将我们优化的QST测量设置的重建的保真度与仅使用产品基础的最先进方案进行比较,我们证明了在现实噪声水平下使用纠缠闸门进行有效QST测量方案的好处。
Quantum state tomography (QST) represents an essential tool for the characterization, verification, and validation (QCVV) of quantum processors. Only for a few idealized scenarios, there are analytic results for the optimal measurement set for QST. E.g., in a setting of non-degenerate measurements, an optimal minimal set of measurement operators for QST has eigenbases which are mutually unbiased. However, in other set-ups, dependent on the rank of the projection operators and the size of the quantum system, the optimal choice of measurements for efficient QST needs to be numerically approximated. We have generalized this problem by introducing the framework of customized efficient QST. Here we extend customized QST and look for the optimal measurement set for QST in the case where some of the quantum gates applied in the measurement process are noisy. To achieve this, we use two distinct noise models: first, the depolarizing channel, and second, over- and under-rotation in single-qubit and to two-qubit gates (for further information, please see Methods). We demonstrate the benefit of using entangling gates for the efficient QST measurement schemes for two qubits at realistic noise levels, by comparing the fidelity of reconstruction of our optimized QST measurement set to the state-of-the-art scheme using only product bases.