Quantum interference is a challenging phenomenon in quantum optics. According to this principle of superposition of quantum mechanics, elementary particles such as photon can not only be in more than one place at a given time, but that an individual particle can cross its own trajectory and interfere with the direction of its path. Thomas Young devised the double slit experiment to prove that light consisted of waves. Analysis of the double slit experiment and the interference pattern indicates that each photon not only goes through both the slits simultaneously, but traverses every possible trajectory on the way to the target, not just in theory, but in fact. In the present work we have analysed the situation in terms of quantum superposition and Schrodinger cat states in quantum optics. The nature of photon in this analysis is examined
Quantum interference is a challenging phenomenon in quantum optics. According to this principle of superposition of quantum mechanics, elementary particles such as photon can not only be in more than one place at a given time, but that an individual particle can cross its own trajectory and interfere with the direction of its path. Thomas Young devised the double slit experiment to prove that light consisted of waves. Analysis of the double slit experiment and the interference pattern indicates that each photon not only goes through both the slits simultaneously, but traverses every possible trajectory on the way to the target, not just in theory, but in fact. In the present work we have analysed the situation in terms of quantum superposition and Schrodinger cat states in quantum optics. The nature of photon in this analysis is examined
3.1 Interference of a Single Photon The kinds of study originally conducted by Thomas Young - in particular, the celebrated "double slit" experiment that we briefly examined in Chapter 1 (see Fig. 1) - provide a capacity to reveal far more than the wave nature of light, important as that is. True enough, the observed characteristic fringe pattern, when monochromatic light passes through two closely spaced slits onto a screen, appears to be simply explicable on the basis of waves from each slit undergoing constructive and destructive interference at different positions on the screen. Yet, astonishingly, these patterns of interference are still exhibited when individual photons of a low-intensity input beam reach the screen one at a time, showing that it cannot in fact be a matter of different photons having to interfere with each other. Indeed, Dirac enunciated the general principle that photons can never directly interact with each other. The double slit and other such experiments indicate that each photon interacts in a delocalized, wave-like manner with both slits at the same time. Successive experiments build interference patterns that conform to an exact mathematical distribution formula, but the position at which an individual photon is detected in any particular instance cannot be predicted; this is a quintessential illustration of quantum uncertainty. Using the path integral approach of quantum theory, the phenomenon is more accurately represented by introducing a summation over all possible routes between the source and the screen on which the pattern appears, signifying an entire "lifetime" for each photon involved in the experiment. This relates to the fact that the actual trajectory is unknown without an observation, and thus we only obtain the probabilities of the photon striking the screen at different positions and times; all trajectories (potentialities) must be considered in a superposition. Each route is considered equally probable, and the variation in phase produces quantum interference. The differences in phase of each trajectory, at varying positions on the screen, generates the fringe pattern. An intriguing variation on this experiment involves "marking" the photons so that the actual route of each photon to the screen is known. Remarkably, in such a case, the fringe patterns do not appear because quantum interference cannot occur. A consequence of the observation of the photon route is an effect that, in other quantum mechanical connections, is known as a collapse of the wavefunction. However, it is possible for the fringe patterns to reappear when information on the route of the photons is lost; this is known as a quantum eraser.
The double-slit experiment in quantum mechanics is an experiment devised by physicist Thomas Young. It shows that light has both a wave nature or characteristic and a particle nature or characteristic, and that these natures are inseparable. So light is said to have wave–particle duality rather than be only a wave or only a particle. The same is true of electrons and other quantum particles. Although Christiaan Huygens thought that light was a wave, Isaac Newton did not. Newton felt that there were other explanations for color, and for the interference and diffraction effects that were observable at the time. Owing to Newton’s tremendous stature, his view generally prevailed. The fact that Huygens’s principle worked was not considered evidence that was direct enough to prove that light is a wave. The acceptance of the wave character of light came many years later when, in 1801, the English physicist and physician Thomas Young (1773–1829) did his now-classic double slit experiment
Schrödinger's cat has long been interpreted by the mainstream as intuitive proof of quantum superposition, but its original intention was Schrödinger's irony and reduction to absurdity of the Copenhagen interpretation. This paper points out that the so-called quantum superposition is not the real physical state of microscopic particles, but the uncertainty phenomenon caused by limited observation methods and inevitable measurement interference. Modern double-slit experiments have realized the emission of single electrons and single photons one by one. Even if only one particle is emitted each time, interference fringes still appear after accumulation. This fact directly proves that each particle has a unique and definite position and path at any time, rather than a superposition state passing through double slits simultaneously. The fundamental reason why a single particle can produce interference is that the particle itself vibrates continuously and has wave properties, rather than a metaphysical superposition state. From the four aspects of original intention, experimental evidence, physical nature and logical judgment, this paper thoroughly clarifies the conceptual substitution of superposition, reveals the objective laws of reality, certainty and uniqueness in the microscopic world, and calls on physics to return to rationality, logic and common sense.
Young’s double slit experiments revived the wave theory of light. The standard interpretation is that the light behaves as waves before and after passing through the double slit, and the superposition of waves produces the interference pattern. Feynman called the double slit experiment the only mystery in quantum mechanics. In this article, we experimentally show the novel universal phenomena: (1) the light is particles, but waves: within macro-distance from a diaphragm, the light rays produce non-interference patterns; while near the screen, the photons produce orthogonal interference patterns; (2) the non-interference patterns evolve to the orthogonal interference patterns gradually in the same experiment; (3) the evolution of the patterns cannot be interpreted by either classic optics or the quantum optics; (4) the non-interference patterns and the orthogonal interference patterns can show on the screen simultaneously; (5) The convex lens stops the further evolution. The experiments: (1) challenge the classical optics and quantum optics; (2) violate both Bohr’s complementarity principle and wave particle duality; (3) provide profound phenomena for developing optics and for studying the nature of light; (4) suggest that a complete theory should be able to consistently interpret all phenomena, including the non-interference pattern, the interference pattern, and the evolution from the non-interference to the interference pattern in the same wave experiment.
This experiment explores the quantum phenomenon known as the Quantum Eraser, using a variation of Young’s Double Slit experiment. Young’s Double Slit experiment demonstrates that light acts as a wave by creating an interference pattern when diffracted through two slits. If one measures which of the two slits the photons pass through, then the interference pattern is replaced by a single bright spot, as would be expected for particle-like behaviour. The “Quantum Eraser” eliminates the measurement on the photons, thereby reintroducing the interference pattern observed in Young’s original experiment. The experiment’s first stage saw Young’s Double Slit experiment recreated and an interference pattern was observed. Upon adding two orthogonally polarized filters, the photon’s path was measured, and the interference pattern was removed. By then adding a third filter which was polarized 45O relative to both other polarisers, the interference pattern was somewhat restored. For each experiment, the heights of the peaks in the interference patterns were compared to each other to examine the quality of the reproduced interference pattern based on the original double slit interference pattern. This comparison gave a quantitative result that demonstrated that the Quantum Eraser was able to restore the interference pattern to within 5 standard errors, thereby exemplifying the effect that changing the measurement conditions affects the final measurement.
Young’s double slit experiments, which represent the mystery of quantum mechanics, have been interpreted by quantum probability waves and pilot waves. In this article, to study the mystery, we introduce the “virtual box” which represents the slide of double-slit and its right-hand neighborhood. Within, and only within, the “virtual box” the standard wave interference patterns are formed. We propose and carry out “comprehensive double slit experiments” that show that, first, light travelling from a laser source towards the slides of double slit and/or cross-double slit behaves as particle (postulate-1), and second, after leaving the "virtual box" zone and being directed towards the detector, the light behaves as a stream of photons (postulate-2) with no further interference due to the slits. On the one hand, the interference patterns do exist in the comprehensive-double slit experiments. On the other hand, we show four novel phenomena: (1) the fringes of the interference patterns are formed independently; (2) the fringes of the interference patterns can be formed partially; (3) the longitudinal shields do not disturb the interference patterns; and (4) the range of the virtual box is less than one inch. These novel phenomena indicate that photons behave as particles, and would not be expected if photons behave as waves created by the double slit and/or cross double slit. The comprehensive-double slit experiments show the coexistence of wave distribution and particle nature of photons in the same experiment, which violates complementarity principle and thus, seems a paradox. We suggest an interpretation to address the paradox. All observations of the comprehensive-double slit experiments are consistent. Progress in studying the mystery of the double slit experiment is presented.