论文标题
无想像量子多参数估计
Imaginarity-free quantum multiparameter estimation
论文作者
论文摘要
通过以下三个障碍，难以使多参数量子估计。首先，不同物理数量之间的不相容性限制了可达到的精度。其次，直到发现最佳测量值之前，最终的精度才饱和。第三，最佳测量通常可能取决于参数的目标值，因此对于未知目标状态可能无法执行。 我们提出了一种规避这三个障碍的方法。一类量子统计模型，利用反对对称性或等效的真实密度矩阵提供兼容的多参数估计。对称性伴随着纯状态模型的目标无关的最佳测量。基于这一发现，我们提出了实施量子计量方案的反对对称对称性的方法。我们进一步引入了一个函数，该函数将量子统计模型的反自然不对称性作为表征相变量子的潜在工具。
Multiparameter quantum estimation is made difficult by the following three obstacles. First, incompatibility among different physical quantities poses a limit on the attainable precision. Second, the ultimate precision is not saturated until you discover the optimal measurement. Third, the optimal measurement may generally depend on the target values of parameters, and thus may be impossible to perform for unknown target states. We present a method to circumvent these three obstacles. A class of quantum statistical models, which utilizes antiunitary symmetries or, equivalently, real density matrices, offers compatible multiparameter estimations. The symmetries accompany the target-independent optimal measurements for pure-state models. Based on this finding, we propose methods to implement antiunitary symmetries for quantum metrology schemes. We further introduce a function which measures antiunitary asymmetry of quantum statistical models as a potential tool to characterize quantumness of phase transitions.
