We already know the unconventional and inexplicable behavior of light/photons (and other quantum particles such as electrons) in the Which-Way quantum experiment and entanglement phenomena. In this paper we propose another quantum experiment using a Michelson interferometer. We start with an 'elementary' thought experiment. Suppose that a Michelson interferometer is set up so that the two light beams undergo complete constructive interference, with a single bright spot. Then the distance of one of the mirrors is slightly adjusted for a complete destructive interference: the bright spot disappears. The puzzle is: where does the light go? We suspect that, just like nature does not allow us to know which slit a photon has passed through in the double- slit experiment, nature may not allow us to know 'where the light goes' in the case of (complete) destructive interference. Although nature may not allow a direct measurement, we can understand by reasoning 'where the light goes' during complete destructive interference. This paper reveals the mystery. A simple quantum experiment based on the Michelson interferometer is proposed.
We already know the unconventional and inexplicable behavior of light/photons (and other quantum particles such as electrons) in the Which-Way quantum experiment and entanglement phenomena. In this paper we propose another quantum experiment using a Michelson interferometer. We start with an 'elementary' thought experiment. Suppose that a Michelson interferometer is set up so that the two light beams undergo complete constructive interference, with a single bright spot. Then the distance of one of the mirrors is slightly adjusted for a complete destructive interference: the bright spot disappears. The puzzle is: where does the light go? We suspect that, just like nature does not allow us to know which slit a photon has passed through in the double- slit experiment, nature may not allow us to know 'where the light goes' in the case of (complete) destructive interference. Although nature may not allow a direct measurement, we can understand by reasoning 'where the light goes' during complete destructive interference. This paper reveals the mystery. A simple quantum experiment based on the Michelson interferometer is proposed.
We already know the unconventional and inexplicable behavior of light/photons (and other quantum particles such as electrons) in the Which-Way quantum experiment and entanglement phenomena. In this paper we propose another quantum experiment using a Michelson interferometer. We start with an 'elementary' thought experiment. Suppose that a Michelson interferometer is set up so that the two light beams undergo complete constructive interference, with a single bright spot. Then the distance of one of the mirrors is slightly adjusted for a complete destructive interference: the bright spot disappears. The puzzle is: where does the light go? We suspect that, just like nature does not allow us to know which slit a photon has passed through in the double- slit experiment, nature may not allow us to know 'where the light goes' in the case of (complete) destructive interference. Although nature may not allow a direct measurement, we can understand by reasoning 'where the light goes' during complete destructive interference. This paper reveals the mystery. A simple quantum experiment based on the Michelson interferometer is proposed.
The puzzles of quantum mechanics are: 1. what is the medium for the photon and for the electron wave? i.e. what is waving? 2. particle interference pattern 3. observer effect. 4. entanglement. In Quantum Erasure and Double-Slit experiments, how does the emitter know to direct the photon two both slits or only to one slit? And how does the detector know where to detect the photons to form an interference pattern and not a bell-shaped (Gaussian) pattern or vice versa? This paper proposes a few, closely related, simple and subtle laws of nature governing quantum phenomena. Some of the findings in this paper are: 1. A photon is emitted in two steps: the creation of photon path and the emission of the photon 2. Although (almost) all of the energy of the photon is localized in space, the photon extends to infinity. An extremely small energy of the photon, which we call the 'precursor wave' in this paper, extends to infinity. The instant the photon is emitted, its precursor wave creates a path to infinity; it appears instantaneously in all its path to infinity, with infinitely small energy density. The precursor wave serves as the 'highway' for the propagation of the main energy packet. However, to conserve the principle of causality, we assume that the tip of the photon propagates at a speed billions times the speed of light. Thus, there are two speeds associated with the photon: the speed we know as c and the speed at which the photon length increases. 2. A photon will be emitted only towards an absorber. A photon is emitted by the interaction of the emitter and a detector. It is obvious that a photon will not be emitted if there is no emitter. Nor will a photon be emitted if there is no detector . Once a photon is emitted, however, it exists objectively, autonomously. The photon is emitted only after its path is determined by the interaction of the emitter and the absorber, at the instant of emission. 3. The photon energy will be concentrated where there is higher wave amplitude, i.e higher intensity of oscillation of electric and magnetic fields. This results in 'dragging' of the electromagnetic energy by the wave, hence eliminating the need for any medium. It is also proposed that single photon interference is a quantum phenomenon whereas two photon interference is a classical phenomenon. Similar laws hold for the electron. The 'medium' for the electron wave is the electron (the electron mass density field) itself. Where there is higher intensity of electron wave/oscillation, there will be higher electron mass density. This means that the electron wave 'drags' the electron with itself. Therefore, no exotic 'medium' is required for the photon and for the electron wave.
Interference phenomena, such as those observed in Young’s double-slit experiment, are foundational to quantum mechanics, yet their interpretation continues to spark debate. Villas-Boas et al. [Phys. Rev. Lett. 134, 133603 (2025)] propose a quantum-optical framework attributing non-detection in regions of destructive interference to photons occupying ``perfectly dark'' states, which they claim do not interact with a two-level atom sensor due to vanishing coupling in the Jaynes-Cummings Hamiltonian. We argue that this interpretation is fundamentally flawed. Dark states, such as the out-of-phase coherent state ∣α,−α⟩, are readily detectable in alternative experimental setups, including dispersive coupling in cavity QED and photon-counting detectors like photomultiplier tubes or avalanche photodiodes, which are sensitive to the photon number operator. This detectability undermines the assertion that dark states are the intrinsic cause of non-detection in destructive interference regions. Instead, the quantum mechanical superposition principle, combined with the Born rule, fully accounts for interference patterns across all detection schemes, as evidenced by well-established experiments such as single-photon double-slit interference, Hong-Ou-Mandel two-photon interference, and cavity QED measurements. By overgeneralizing a detector-specific effect, the dark-state framework introduces an unnecessary and redundant construct, as the standard quantum mechanical formalism already provides a complete and experimentally validated explanation of interference phenomena.
Over the past several decades, single photon-based path interference in double-slit experiment has been well demonstrated for the particle nature of photons satisfying complementarity theory, where the quantum mechanical interpretation of the single photon interference fringe is given by Born rule for complex amplitudes in measurements. Unlike most conventional methods using entangled photon pairs, here, a classical coherent light source is directly applied for the proof of the same self-interference phenomenon. Instead of double slits, we use a Mach-Zehnder interferometer as usual, where the resulting self-interference fringe of coherent single photons is exactly the same as that of the coherent photon ensemble of the laser, demonstrating that the classical coherence based on the wave nature is rooted in the single photon self-interference. This unexpected result seems to contradict our common understanding of decoherence phenomena caused by multi-wave interference among bandwidth distributed photons in coherence optics.
Abstract: This paper examines the Double-Slit Interference Thought Experiment to demonstrate that light quanta do not exhibit wave-particle duality under the condition that the experiment is successful. The essence of light quanta is that of pure particles. The thought experiment of light quanta undergoing double-slit interference is pivotal in proving that light quanta, along with other particles such as electrons, atoms, and macromolecules, are purely particulate in nature. In space, photons can interfere with each other's paths based on their momentum. This interference can simultaneously alter the trajectory and even the velocity of photons. That is, a photon beam with greater momentum may carry along a portion of beams with lesser momentum, propagating them over considerable distances. The wavelength of a light wave fundamentally represents the distance between consecutive photons as they queue and advance through space. A longer wavelength corresponds to a greater distance between photons, causing them to diverge more widely in space, as seen with radio waves. Conversely, a shorter wavelength implies closer proximity between photons, resulting in more tightly packed emission and a highly directional nature, as seen in gamma rays. Photons in the visible spectrum may occasionally transmit information with specific content. This information, conveyed via photons, can propagate over distances ranging from several metres to thousands of kilometres.
Double-double-slit thought experiment provides profound insight on interference of quantum entangled particles. This paper presents a detailed experimental realisation of quantum double-double-slit thought experiment with momentum entangled photons and theoretical analysis of the experiment. Experiment is configured in such a way that photons are path entangled and each photon can reveal the which-slit path information of the other photon. As a consequence, single photon interference is suppressed. However, two-photon interference pattern appears if locations of detection of photons are correlated without revealing the which-slit path information. It is also shown experimentally and theoretically that two-photon quantum interference disappears when the which-slit path of a photon in the double-double-slit is detected.