Delayed choice and quantum eraser experiments have attracted much interest recently, both theoretically and experimentally. In particular, they have prompted suggestions that quantum mechanics involves acausal effects. Using a recently developed approach which takes apparatus into account, we present a detailed analysis of various double-slit experiments to show that this is never the case. Instead, quantum experiments can be described in terms of a novel concept of time called stages. These can cut across the conventional linear time parameter as experienced in the laboratory and appear to violate causality.
Quantum superposition is the cornerstone of quantum mechanics, where interference fringes originate in the self-interference of a single photon via indistinguishable photon characteristics. Wheeler delayed-choice experiments have been extensively studied for the wave-particle duality over the last several decades to understand the complementarity theory of quantum mechanics. The heart of the delayed-choice quantum eraser is in the mutually exclusive quantum feature violating the cause-effect relation. Here, we experimentally demonstrate the quantum eraser using coherent photon pairs by the del…
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 eras…
Quantum entanglement is known as a unique feature of quantum mechanics, which cannot be obtained from classical physics. Recently, a coherence interpretation has been conducted for the delayed-choice quantum eraser using coherent photon pairs, where phase-locked symmetric frequency detuning between paired photons plays an essential role for selective measurement-caused nonlocal correlation. Here, a macroscopic version of the nonlocal correlation is presented using orthogonally polarized optical fields in a continuous wave quantum eraser scheme in a Mach-Zehnder interferometer (MZI). The result…
Wheeler's delayed-choice experiment was conceived to illustrate the paradoxical nature of wave-particle duality in quantum mechanics. In the experiment, quantum light can exhibit either wave-like interference patterns or particle-like anti-correlations, depending upon the (possibly delayed) choice of the experimenter. A variant known as the quantum eraser uses entangled light to recover the lost interference in a seemingly nonlocal and retrocausal manner. Although it is believed that this behavior is incompatible with classical physics, here we show that the observed quantum phenomena can be r…
The delayed-choice quantum eraser has long been a subject of controversy, and has been looked at as being incomprehensible to having retro-causal effect in time. Here the delayed-choice quantum eraser is theoretically analyzed using standard quantum mechanics. Employing Mach-Zehnder interferometer, instead of a conventional two-slit interference, brings in surprising clarity. Some common mistakes in interpreting the experiment are pointed out. It is demonstrated that in the delayed mode there is no which-way information present after the particle is registered on the screen or the final detect…
The quantum eraser variant of the double-slit experiment, and its 'delayed choice' sub-variant, are considered from the perspective of weak value and weak measurement theory (which is briefly reintroduced here). The interference fringes that appear when measuring certain spin states, which can then be 'erased' when measuring other spin states, are shown to be anomalous weak values that depend on particular post-selection choices. By framing the choice of spin measurement as a weak value of a certain weak measurement, it is then made clear what physical claims can and cannot be made about what …
Indistinguishability is an essential concept to understanding mysterious quantum features in the view point of the wave-particle duality of quantum mechanics. The fundamental physics of the indistinguishability lies in quantum superposition of a single photon via orthogonal bases in a Hilbert space. Here, a pure coherence approach is applied to the nonlocal correlation using coherent photons manipulated for polarization-frequency correlation. For this, both wave mixing and heterodyne detection techniques are applied for the delayed-choice experiments of a quantum eraser using coherent photons …
Institute of Quantum Technologies and Advanced Computing, KACST（KACST量子技术与先进计算研究所）；Department of Physics, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU)（伊玛目穆罕默德·本·沙特伊斯兰大学理学院物理系）；Department of Physics, College of Science, King Khalid University（国王哈立德大学理学院物理系）；Institute for Quantum Science and Technology and Department of Physics, Shanghai University（上海大学量子科学与技术研究院及物理系）；Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University（上海大学高温超导学重点实验室）；NCQOQI, KACST（KACST国家量子光学与量子信息研究中心）
The assertion by Yu and Nikolic that the delayed choice quantum eraser experiment of Kim et al. empirically falsifies the consciousness-causes-collapse hypothesis of quantum mechanics is based on the unfounded and false assumption that the failure of a quantum wave function to collapse implies the appearance of a visible interference pattern.
Computer simulation of Wheeler's delayed choice experiment with photons
我们提出了一个惠勒延迟选择实验的计算机模拟模型，该模型是最近报道的一个实验的一对一复制（V. Jacques { \sl et al.}，Science 315，966（2007））。该模型完全基于实验事实，满足爱因斯坦的局部因果关系标准，不依赖于任何量子理论的概念。然而，模拟模型再现了惠勒延迟选择实验的量子理论描述所获得的平均值。我们的结果证明，它是可能的，以粒子的惠勒的延迟选择实验，再现从量子理论计算的平均值，这并不违背常识的描述。
惠勒的延迟选择实验研究了波粒二象性的不确定性和测量仪器在量子理论中所扮演的角色。由于与经典物理学的不一致，人们普遍认为不可能用隐变量理论重现延迟选择实验。最近的研究表明，这种假设是错误的，事实上惠勒的延迟选择实验可以用因果二维隐变量理论来解释[R。Chaves，G. B. Lemos，and J. Pienaar，Phys. Rev. Lett. 120，190401（2018）]。在这里，我们进行了一个实验的设备无关的延迟选择实验使用的光子状态是空间分离的，并证明了一个无漏洞版本的延迟选择协议是符合量子理论，但不符合任何因果关系的二维隐变量理论。这挽救了惠勒的思想实验，并表明因果关系可以用来检验量子理论，以补充贝尔和莱格特-加格检验。
