Double-slit diffraction studies with photons or massive particles rank among the most beautiful experiments in physics. In particular, measurements at very low intensities demonstrate the particle-wave duality and the coherent superposition of states very clearly. In this paper, low-intensity double-slit experiments in the time domain are presented measuring the spectral distribution of synchrotron light from a single relativistic electron in a storage ring. In two consecutive radiation sources (so-called undulators) with a magnetic detour between them, electrons emit two temporally separated light pulses leading to a spectrum with interference fringes, very much like the angular distribution of light behind two spatially separated slits. Independent experiments at two synchrotron light sources (DELTA in Germany and UVSOR-III in Japan) directly demonstrate that the spectral distribution of accumulated synchrotron light from a single electron is essentially the same as the spectrum from a beam of many electrons. While the latter is usually explained as interference between electromagnetic waves from the two undulators, the single-electron experiments demonstrate that coherent photon emission is delocalized over several meters and the accumulated spectral distribution exhibits a deterministic interference pattern at small wavelengths. The experiments presented here were conducted with near-ultraviolet light to avoid an elaborate in-vacuum setup, but the very wide spectral range of synchrotron radiation, from infrared light to X-rays, enables access to regimes not available in laser-based quantum optics experiments.
Double-slit diffraction studies with photons or massive particles rank among the most beautiful experiments in physics. In particular, measurements at very low intensities demonstrate the particle-wave duality and the coherent superposition of states very clearly. In this paper, low-intensity double-slit experiments in the time domain are presented measuring the spectral distribution of synchrotron light from a single relativistic electron in a storage ring. In two consecutive radiation sources (so-called undulators) with a magnetic detour between them, electrons emit two temporally separated light pulses leading to a spectrum with interference fringes, very much like the angular distribution of light behind two spatially separated slits. Independent experiments at two synchrotron light sources (DELTA in Germany and UVSOR-III in Japan) directly demonstrate that the spectral distribution of accumulated synchrotron light from a single electron is essentially the same as the spectrum from a beam of many electrons. While the latter is usually explained as interference between electromagnetic waves from the two undulators, the single-electron experiments demonstrate that coherent photon emission is delocalized over several meters and the accumulated spectral distribution exhibits a deterministic interference pattern at small wavelengths. The experiments presented here were conducted with near-ultraviolet light to avoid an elaborate in-vacuum setup, but the very wide spectral range of synchrotron radiation, from infrared light to X-rays, enables access to regimes not available in laser-based quantum optics experiments.
We present a new realization of the time-domain double-slit experiment with photoelectrons, demonstrating that spontaneous radiation from a bunch of relativistic electrons can be used to control the quantum interference of single-particles. The double-slit arrangement is realized by a pair of light wave packets with attosecond-controlled spacing, which is naturally included in the spontaneous radiation from two undulators in series. Photoelectrons emitted from helium atoms are observed in the energy-domain under the condition of detecting them one by one, and the stochastic buildup of the quantum interference pattern on a detector plane is recorded.
Abstract The paper presents the results of a quantum interference study using an asymmetrical double-slit experiment with a low-intensity laser beam, conducted in the single-photon approximation and the Fresnel near-field transition pre-Fraunhofer condition. In addition to the temporal separation achieved by recording each particle individually, the hybrid-asymmetrical double-slit design (in both width and height) also allows spatial separation of the first satellite diffraction bands created by each slit, thereby minimising the mixing background effects from the opposite slit. Isolating the satellite bands of a diffraction pattern from one of the two slits enables which-way identification of the quantum particle, contributing maximally to the path-distinguishability parameter D=1. Within these satellite bands, we observed interference fringes with reliability at their diffraction peaks for the wide slit and the narrow slit. After subtracting multiphoton-mixing interference noises V(mix), we obtain significant single-photon wave visibility values = 0.051±.009(stat.+sys.) and = 0.065±.009(stat.+sys.), respectively, at the wide-slit I1 and narrow-slit I2 diffraction bands. The results suggest the possibility of establishing an unusual correlation, D + V > 1, in which a significant number of photons exhibit both wave and particle properties simultaneously within the same experimental spectrum. This differs from the Copenhagen interpretation and therefore requires further explanation. PACS numbers: 03.65.-w, 03.65.Ta, 42.50.Xa
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.
The double-slit experiment strikingly demonstrates the wave-particle duality of quantum objects. In this famous experiment, particles pass one-by-one through a pair of slits and are detected on a distant screen. A distinct wave-like pattern emerges after many discrete particle impacts as if each particle is passing through both slits and interfering with itself. Here we present a temporally- and spatially-resolved measurement of the double-slit interference pattern using single photons. We send single photons through a birefringent double-slit apparatus and use a linear array of single-photon detectors to observe the developing interference pattern. The analysis of the buildup allows us to compare quantum mechanics and the corpuscular model, which aims to explain the mystery of single-particle interference. Finally, we send one photon from an entangled pair through our double-slit setup and show the dependence of the resulting interference pattern on the twin photon's measured state. Our results provide new insight into the dynamics of the buildup process in the double-slit experiment, and can be used as a valuable resource in quantum information applications.
We construct proper microscopic propositions to consistently capture and explain the interference patterns obtained for electrons and photons, detected individually or otherwise, in one- and two-slit experiments. We propose that for single-photon detections (after time integration), no interference pattern is obtained if one uses non-transparent slit material with slit holes (not diffraction slits). The non-transparent slit material does not permit photons to transmit, reflect internally nor refract. However, the same slit holes can produce the usual interference pattern with electromagnetic waves due to interfering in-phase and out-of-phase light waves. As for the electrons, detected individually or not, partial interference patterns can always be obtained from the two-slit experiment when one of the slits is closed (one at a time), which then can be manually overlapped to produce the complete interference pattern of a double-slit experiment. These new theoretically constructed experimental results for photons and electrons can be readily verified with our current technology using suitable optically non-transparent (for photons) and highly insulating (for electrons) slit materials.
The particle- interference-experiments, with the photons and electrons have clearly shown that they are always detected as localized „particles‟; and the density of their detections exhibit a pattern similar to the interference of waves. This experimental-observation is now explained here, making the current, „probabilistic interpretation‟, a past history. The „particle ‟ is first mathematically characterized as an „impulse function ‟ in space; and then Fourier-transformed into the wave-number-domain, as a wide band of constituent-waves as shown in the fig. 1&2. The „particle ‟ is explained as an „event ‟ of constructive-superimposition of a wide band of „pre-quantum-waves‟. This „event ‟ occurs in space at regular distances; and at regular instances in time. We know that even the purest monochromatic laser source has a „line-width ‟ of a few Giga-Hertz, or at least a few kilo-Hertz. So in the particle-interference-experiments, they are these wide bands of waves which pass through both the slits, even in the case of single photon states, and interfere physically. This physical interference of the wide bands of pre-quantum-waves determines the position and time of emergence of the „particle‟. Thus, form the theoretical view-point, there are only the waves, and waves alone; and the „particle ‟ is a specific situation of constructive-superimposition of all the spectral-components of pre-quantum-waves; so there is no wave-particle-duality.