A realizable delayed-choice quantum eraser, using a modified Mach-Zehnder (MZ) interferometer and polarization entangled photons, is theoretically analyzed here. The signal photon goes through a modified MZ interferometer, and the polarization of the idler photon provides path information for the signal photon. The setup is very similar to the delayed-choice quantum eraser experimentally studied by the Vienna group. In the class of quantum erasers with discrete output states, it is easy to see that the delayed mode leaves no choice for the experimenter. The which-way information is always erased, and every detected signal photon fixes the polarization state of the idler, and thus gives information on precisely how the signal photon traversed the two paths. The analysis shows that the Vienna delayed-choice quantum eraser is the first experimental demonstration of the fact that the delayed mode leaves no choice for the experimenter, and the which-way information is always erased. Additionally it is shown that this argument holds even in a conventional two-slit quantum eraser. Every photon registered anywhere on the screen, fixes the state of the two-state which-way detector in a unique mutually unbiased basis. In the delayed-choice quantum eraser experiments, the role of mutually unbiased basis sets for the which-way detector, has been overlooked till now.

这里从理论上分析了一种可实现的延迟选择量子擦除器，它使用改进的 Mach-Zehnder (MZ) 干涉仪和偏振纠缠光子。信号光子通过改进的 MZ 干涉仪，惰光子的偏振为信号光子提供路径信息。该设置与维也纳小组实验研究的延迟选择量子橡皮擦非常相似。在具有离散输出状态的量子擦除类中，很容易看出延迟模式给实验者留下了别无选择的余地。哪个方向的信息总是被删除，每个检测到的信号光子都会固定惰轮的偏振态，从而提供关于信号光子如何准确穿过两条路径的信息。分析表明，Vienna延迟选择量子擦除器是延迟模式让实验者别无选择的事实的第一个实验证明，并且始终擦除了哪个方向的信息。此外还表明，即使在传统的双缝量子擦除器中，这一论点也成立。在屏幕上任何位置注册的每个光子，都以独特的互不偏置的方式固定双态哪个方向检测器的状态。在延迟选择量子擦除实验中，互无偏基组对哪个方向检测器的作用一直被忽视。在屏幕上任何位置注册的每个光子，都以独特的互不偏置的方式固定双态哪个方向检测器的状态。在延迟选择量子擦除实验中，互无偏基组对哪个方向检测器的作用一直被忽视。在屏幕上任何位置注册的每个光子，都以独特的互不偏置的方式固定双态哪个方向检测器的状态。在延迟选择量子擦除实验中，互无偏基组对哪个方向检测器的作用一直被忽视。