Wheeler's Delayed-choice Experiment Research Articles

Proposal for sequential Stern–Gerlach experiment with programmable quantum processors

The historical significance of the Stern–Gerlach (SG) experiment lies in its provision of the initial evidence for space quantization. Over time, its sequential form has evolved into an elegant paradigm that effectively illustrates the fundamental principles of quantum theory. To date, the practical implementation of the sequential SG experiment has not been fully achieved. In this study, we demonstrate the capability of programmable quantum processors to simulate the sequential SG experiment. The specific parametric shallow quantum circuits, which are suitable for the limitations of current noisy quantum hardware, are given to replicate the functionality of SG devices with the ability to perform measurements in different directions. Surprisingly, it has been demonstrated that Wigner’s SG interferometer can be readily implemented in our sequential quantum circuit. With the utilization of the identical circuits, it is also feasible to implement Wheeler’s delayed-choice experiment. We propose the utilization of cross-shaped programmable quantum processors to showcase sequential experiments, and the simulation results demonstrate a strong alignment with theoretical predictions. With the rapid advancement of cloud-based quantum computing, such as BAQIS Quafu, it is our belief that the proposed solution is well-suited for deployment on the cloud, allowing for public accessibility. Our findings not only expand the potential applications of quantum computers, but also contribute to a deeper comprehension of the fundamental principles underlying quantum theory.

Why interference phenomena do not capture the essence of quantum theory

Quantum interference phenomena are widely viewed as posing a challenge to the classical worldview. Feynman even went so far as to proclaim that they are the only mystery and the basic peculiarity of quantum mechanics. Many have also argued that basic interference phenomena force us to accept a number of radical interpretational conclusions, including: that a photon is neither a particle nor a wave but rather a Jekyll-and-Hyde sort of entity that toggles between the two possibilities, that reality is observer-dependent, and that systems either do not have properties prior to measurements or else have properties that are subject to nonlocal or backwards-in-time causal influences. In this work, we show that such conclusions are not, in fact, forced on us by basic interference phenomena. We do so by describing an alternative to quantum theory, a statistical theory of a classical discrete field (the `toy field theory') that reproduces the relevant phenomenology of quantum interference while rejecting these radical interpretational claims. It also reproduces a number of related interference experiments that are thought to support these interpretational claims, such as the Elitzur-Vaidman bomb tester, Wheeler's delayed-choice experiment, and the quantum eraser experiment. The systems in the toy field theory are field modes, each of which possesses, at all times, both a particle-like property (a discrete occupation number) and a wave-like property (a discrete phase). Although these two properties are jointly possessed, the theory stipulates that they cannot be jointly known. The phenomenology that is generally cited in favour of nonlocal or backwards-in-time causal influences ends up being explained in terms of inferences about distant or past systems, and all that is observer-dependent is the observer's knowledge of reality, not reality itself.

Photon’s Spin Mechanism and Wave-Particle Hybrid Structure. It Exhibits both Wave Property and Particle Property at the Same Time in all Experiments.

The interpretation of single photon double slits Wheeler's delayed choice experiment leads to a weird inference: "what the observer does now can change what happened in the past". It subverts our cognitions. Other interpretations are also in dispute. Is there another possible way that can better explain experiments? For this purpose, we try to reacquaint what is a photon? What structure does it have? How does the structure influence the photon behavior? In 1905 Einstein supposed that the photon is a quantum of EM radiation; according to the quantum interpretation, the probability density of a coherent state undergoes a sinusoidal vibration with time. It will also excite a quantized EM wave. So, our research object must be an EM wave beams. We discover and prove that under the Quantification Law of Charge, there is a kind of axial symmetric EM-wave beam it is a quantum of circularly polarized light. Its energy is concentrated in a very small packet; this energy packet will be proved having the photon properties, like , , spin , obeying B-E statistics and so on; On the other hand, the width of the sodium spectral lines identifies that the energy packet carries a long EM wave beam. They form a wave-particle hybrid structure. It exhibits both wave property and particle property at the time in all experiments. Its interpretation for the single photon double slits Wheeler's delayed choice experiment does not lead to the above strange inference.

Photon Wave-particle Hybrid Structure and Wheeler’s Single Photon Double-slit Delayed Choice Experiment

The interpretation of single-photon double slit Wheeler's delayed choice experiment leads to a weird inference: "what observer does now can change what happened in the past". It subverts our cognitions. Other interpretations are also in dispute. I try to find another possible way that can better explain the experiments. For this purpose, we try to reacquaint what is a photon; what structure it possesses, and how the structure influences photon behavior. In 1905 Einstein supposed that the photon is a quantum of EM radiation; according to the quantum interpretation, the probability density of a coherent state undergoes a sinusoidal vibration with time; it will also excite a quantized EM wave. So we start our research from an axially symmetric EM wave beam. We discovered and proved that under the Quantification Law of Charge, there is a kind of axially symmetric EM-wave beam which is a quantum of circularly polarized light. Its energy is concentrated in a very small packet; this energy packet will be proven to have photon properties, like,, spin , obeying B-E statistics, etc. On the other hand, the width of the sodium spectral lines identifies that the energy packet carries a long EM wave beam. They form a wave-particle hybrid structure. It exhibits both wave property and particle property all the time in the experiments. Its interpretation for the single photon double slits Wheeler's delayed choice experiment does not lead to the above strange inference.

Modified quantum delayed-choice experiment without quantum control or entanglement assistance

Wheeler's delayed-choice experiment delays the decision to observe either the wave or particle behavior of a photon until after it has entered the interferometer, and the quantum delayed-choice experiment provides the possibility of observing the wave and particle behaviors with a single experimental setup by introducing quantum control. We here propose a modified quantum delayed-choice experiment without quantum control or entanglement assistance, in which a photon can be prepared in a wave-particle superposition state and the morphing behavior of wave-to-particle transition can be observed easily. It is demonstrated that the presented scheme can allow us to rule out classical hidden-variable models in a device-independent manner via violating dimension witness. We also extend the scheme to the situation of two degrees of freedom, first constructing a hybrid quantum delayed-choice experiment which enables a photon respectively exhibits wave and particle behaviors in different degrees of freedom, and then proposing a scheme to prepare the single-photon wave-particle entanglement. This study is not only meaningful to explore the wave-particle complementarity of photons, but also provides potential for the research of the single-particle nonlocality from the perspective of the wave-particle degree of freedom.

Classical model of a delayed-choice quantum eraser

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 reproduced by adopting a simple deterministic detector model and supposing the existence of a random zero-point electromagnetic field.

Multipath wave-particle duality with a path detector in a quantum superposition

According to Bohr's principle of complementarity, a quanton can behave either as a wave or a particle, depending on the choice of the experimental setup. Some recent two-path interference experiments have devised methods where one can have a quantum superposition of the two choices, thus indicating that a quanton may be in a superposition of wave and particle nature. These experiments have been of interest from the point of view of Wheeler's delayed-choice experiment. However, it has also been claimed that this experiment can violate complementarity. Here we theoretically analyze a multipath interference experiment that has a which-path detector in a quantum superposition of being present and absent. We show that a tight multipath wave-particle duality relation is respected in all such situations, and complementarity holds well. The apparent violation of complementarity may be due to incorrect evaluation of path distinguishability in such scenarios.

Emergent Universe from Many Unreal World Interpretation

There are multiple interpretations of quantum mechanics, 2 most famous interpretations are Copenhagen interpretation and many world interpretations. Copenhagen interpretation fails to explain the mechanism behind wave function collapse and many world interpretations avoid collapse by adding infinite branching worlds. Goal of this paper is to provide alternate interpretations which explains mechanism behind collapse using finite pre-existent unreal worlds. All quantum weirdness can be narrowed down to few postulates, if we consider every particle has a dedicated address in event horizon, every address has its own dedicated spacetime fabric, particles will have its projected shadows on other space time fabric and whenever there is interaction between true particle and other shadow particle, new address is assigned for both interacting particles and instantaneously all projected shadow becomes void. We perceive universe from collapse perspective only when particles collapse and new address are assigned, thus giving an illusion that we live in one universe but its result of interaction of multiple worlds. From new postulates we were able to explain how one of the entangled photons can decides other photons path in Wheeler's delayed choice experiment and thus helps us to removes problematic retro causality speculation to explain the phenomenon observed in this experiment.

Compatibility of causal hidden-variable theories with a delayed-choice experiment

Wheeler's delayed-choice experiment investigates the indeterminacy of wave-particle duality and the role played by the measurement apparatus in quantum theory. Due to the inconsistency with classical physics, it has been generally believed that it is not possible to reproduce the delayed-choice experiment using a hidden variable theory. Recently, it was shown that this assumption was incorrect, and in fact Wheeler's delayed-choice experiment can be explained by a causal two dimensional hidden-variable theory [R. Chaves, G. B. Lemos, and J. Pienaar, Phys. Rev. Lett. 120, 190401 (2018)]. Here, we carry out an experiment of a device-independent delayed-choice experiment using photon states that are space-like separated, and demonstrate a loophole-free version of the delayed-choice protocol that is consistent with quantum theory but inconsistent with any causal two-dimensional hidden variable theory. This salvages Wheeler's thought experiment and shows that causality can be used to test quantum theory in a complementary way to the Bell and Leggett-Garg tests.

Realization of a causal-modeled delayed-choice experiment using single photons

Wave-particle duality constitutes one of the most intriguing features in quantum physics. A well-known gedanken experiment that provides evidence for this is the Wheeler's delayed-choice experiment based on a Mach-Zehnder interferometer. Many different versions of delayed-choice experiments have been conducted with both classical and quantum detecting devices. Recently, it was proposed that the delayed-choice experiment could be devised from the perspective of device-independent prepare-and-measure scenario. In our work, we experimentally realize this modified version with a deterministic single-photon source, and examine the wave-particle objective in a causal-modeled scheme without assistance of entanglement, which is achieved by violating the dimension witness inequalities. Our experiment also provides an intriguing perspective and exhibits the benefits of studying quantum theory from the casual model point of view.

Observing Wave/Particle Duality of Light Using Topological Charge

Wave particle duality, also called complementarity, is deeply rooted in the heart of quantum theory. It is fully exemplified in the famous Wheeler's delayed choice experiment where the choice of the wave nature (ability to interfere) or the particle like behavior (path distinguishability) is introduced a posteriori. We perform here a delayed choice experiment in a Mach-Zehnder interferometer, using a classical laser beam and twisted light in a given mode. We entangle the polarization and the twisted internal degrees of freedom, with the which-path-information external degree of freedom of the beam. The particle behavior of light arises from the quantization of the orbital angular momentum. It is demonstrated from torque and light power measurements within 10% accuracy. We then experimentally evidence that the particle or wave behavior of light can be chosen a posteriori, even after the light has left the interferometer, at the moment of the detection.

Quantum entanglement, Wheeler’s delayed choice experiment and its explanation on the basis of quantization of fields

The result of Wheeler's delayed choice experiment is a natural consequence of the entanglement of moving photons and particles (atoms, molecules) of the slit through which they move. The inclusion of quantum fields (taking into account that speed of virtual particles is not limited) self-consistently explains why interaction’s propagation velocity after closing one slit is larger than the speed of light.

Restrictions for the causal inferences in an interferometric system

Causal discovery algorithms allow for the inference of causal structures from probabilistic relations of random variables. A natural field for the application of this tool is quantum mechanics, where a long-standing debate about the role of causality in the theory has flourished since its early days. In this paper, a causal discovery algorithm is applied in the search for causal models to describe a quantum version of Wheeler's delayed-choice experiment. The outputs explicitly show the restrictions for the introduction of classical concepts in this system. The exclusion of models with two hidden variables is one of them. A consequence of such a constraint is the impossibility to construct a causal model that avoids superluminal causation and assumes an objective view of the wave and particle properties simultaneously.

Optical proposals for controlled delayed-choice experiment based on weak cross-Kerr nonlinearities

Employing polarization modes of a photon, we propose two theoretical proposals to exhibit the wave---particle duality of the photon with the assistance of weak cross-Kerr nonlinearities. The first proposal is a classical controlled delayed-choice experiment (that is, Wheeler's delayed-choice experiment), where we can observe selectively wave property or particle property of the photon relying on the experimenter's selection, whereas the second proposal is a quantum controlled delayed-choice experiment, by which the mixture phenomenon of a wave and a particle will be exhibited. Both of them can be realized with near-unity probability and embody the charming characteristics of quantum mechanics. The employment of the mature techniques and simple operations (e.g., Homodyne measurement, classical feed forward, and single-photon transformations) provides the feasibility of the delayed-choice experiment proposals presented here.

Proposal for a quantum delayed-choice experiment with a spin-mechanical setup

We describe an experimentally feasible protocol for performing a variant of the quantum delayed-choice experiment with massive objects. In this scheme, a single nitrogen-vacancy (NV) center in diamond driven by microwave fields is dispersively coupled to a massive mechanical resonator. A double-pulse Ramsey interferometer can be implemented with the spin-mechanical setup, where the second Ramsey microwave pulse drives the spin conditioned on the number states of the resonator. The probability for finding the NV center in definite spin states exhibits interference fringes when the mechanical resonator is prepared in a specific number state. On the other hand, the interference is destroyed if the mechanical resonator stays in some other number states. The wavelike and particlelike behavior of the NV spin can be superposed by preparing the mechanical resonator in a superposition of two distinct number states. Thus a quantum version of Wheeler's delayed-choice experiment could be implemented, allowing of fundamental tests of quantum mechanics on a macroscopic scale.

Wheeler's delayed-choice gedanken experiment with a single atom

In a delayed-choice experiment the decision to measure the particle or wave nature comes after the photon enters the interferometer. An atomic version of the experiment provides the same outcome despite the mass and internal structure of the atoms.

Wheeler's delayed-choice experiment: A proposal for the Bragg-regime cavity-QED implementation

Wheeler's delayed-choice experiment highlights strange features of quantum theory such as pre-sensing of the experimental setup by the quantum object and the role of time. A recent proposal for such an experiment with an interferometer having a quantum beam splitter (QBS) [R. Ionicioiu and D. R. Terno, Phys. Rev. Lett. 107, 230406 (2011)] and its subsequent experimental implementations through photonics and NMR have produced results including the modification in the concept of complementarity. Here we propose a matter-wave Mach-Zehnder-Bragg cavity-QED interferometric setup with final QBS engineered through a cavity field that is taken initially in the superposition of zero and one photon. The setup operates through first-order off-resonant Bragg diffraction of the neutral atoms from the cavity fields with the matter wave's particle (wave) nature marked through the absence (presence) of a photon in the final cavity. The proposal, addressing the issue through atomic de Broglie waves, can be executed within the present cavity-QED experimental scenario with appreciable success probability and fidelity.

Experimental observation of simultaneous wave and particle behavior in a narrowband single-photon wave packet

Light's wave-particle duality is at the heart of quantum mechanics and can be well illustrated by Wheeler's delayed-choice experiment. The choice of inserting or removing the second classical (quantum) beam splitter in a Mach-Zehnder interferometer determines the classical (quantum) wave-particle behaviors of a photon. In this paper, we report our experiment using the classical beam splitter to observe the simultaneous wave-particle behaviors in the wave-packet of a narrowband single photon. This observation suggests that it is necessary to generalize the current quantum wave-particle duality theory. Our experiment demonstrates that the produced wave-particle state can be considered an additional degree of freedom and can be utilized in encoding quantum information.

On Delayed Choice and Contingent Absorber Experiments

It is pointed out that a slight variation on the Wheeler Delayed Choice Experiment presents the same challenge to orthodox quantum mechanics as Maudlin-type contingent absorber experiments present to the Transactional Interpretation (TI). Therefore, the latter cannot be used as a basis for refutation of TI.

Entanglement-Enabled Delayed-Choice Experiment

Wave-particle complementarity is one of the most intriguing features of quantum physics. To emphasize this measurement apparatus-dependent nature, experiments have been performed in which the output beam splitter of a Mach-Zehnder interferometer is inserted or removed after a photon has already entered the device. A recent extension suggested using a quantum beam splitter at the interferometer's output; we achieve this using pairs of polarization-entangled photons. One photon is tested in the interferometer and is detected, whereas the other allows us to determine whether wave, particle, or intermediate behaviors have been observed. Furthermore, this experiment allows us to continuously morph the tested photon's behavior from wavelike to particle-like, which illustrates the inadequacy of a naive wave or particle description of light.