Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China.
Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350116, China.
Sci Adv. 2017 May 5;3(5):e1603159. doi: 10.1126/sciadv.1603159. eCollection 2017 May.
Wave-particle complementarity lies at the heart of quantum mechanics. To illustrate this mysterious feature, Wheeler proposed the delayed-choice experiment, where a quantum system manifests the wave- or particle-like attribute, depending on the experimental arrangement, which is made after the system has entered the interferometer. In recent quantum delayed-choice experiments, these two complementary behaviors were simultaneously observed with a quantum interferometer in a superposition of being closed and open. We suggest and implement a conceptually different quantum delayed-choice experiment by introducing a which-path detector (WPD) that can simultaneously record and neglect the system's path information, but where the interferometer itself is classical. Our experiment is realized with a superconducting circuit, where a cavity acts as the WPD for an interfering qubit. Using this setup, we implement the first twofold delayed-choice experiment, which demonstrates that the system's behavior depends not only on the measuring device's configuration that can be chosen even after the system has been detected but also on whether we a posteriori erase or mark the which-path information, the latter of which cannot be revealed by previous quantum delayed-choice experiments. Our results represent the first demonstration of both counterintuitive features with the same experimental setup, significantly extending the concept of quantum delayed-choice experiment.
波粒二象性是量子力学的核心。为了说明这一神秘特征，惠勒提出了延迟选择实验，其中量子系统表现出波动性或粒子性，这取决于实验装置，而实验装置是在系统进入干涉仪之后做出的。在最近的量子延迟选择实验中，通过引入一个可以同时记录和忽略系统路径信息的路径探测器（WPD），在一个闭合和打开的量子干涉仪的叠加中，同时观察到了这两种互补行为。我们提出并实现了一个概念上不同的量子延迟选择实验，通过引入一个可以同时记录和忽略系统路径信息的路径探测器（WPD），但干涉仪本身是经典的。我们的实验是用超导电路实现的，其中一个腔作为干涉量子位的路径探测器。使用这种设置，我们实现了第一个双重延迟选择实验，该实验表明，系统的行为不仅取决于测量设备的配置，甚至可以在系统被检测后选择，而且还取决于我们是否事后擦除或标记路径信息，这是以前的量子延迟选择实验无法揭示的。我们的结果代表了使用相同实验设置同时演示了这两个反直觉特征的首次实验，显著扩展了量子延迟选择实验的概念。
