Double-slit Research Articles

A Unifying Theory for Quantum Physics, Part 1:

Is the quantum world as strange as they say? If this were an unsolved mathematics question, we might try a new angle of attack. We know quantum mechanics (QM) is the most accurate and productive science humans ever had, meaning its probability predictions are accurate. Every probability has two square roots. The Born rule says either would produce the same probability. Assume nature uses the negative of QM’s equations. What could that mean? We’d need to revise Feynman’s path-integrals and Schrödinger’s equation. If waves travel in the opposite direction as what QM believes, that could produce the negative equations. No wave-particle duality. Free particles would follow backwards zero-energy waves coming from detectors. This, surprisingly, gets rid of quantum weirdness. Our proposal is that nature uses the negative of QM’s equations because particles follow zero-energy waves backwards. Considerable evidence fits this model, including a neutron-interferometer and the Davisson-Germer experiments, a quantum-eraser experiment, Wheeler-gedanken and double-slit experiments, Bell-test experiments, Stern-Gerlach, and high-energy scattering experiments. Finally, we propose a plan for how to motivate students to want to study quantum technologies, thereby addressing the most prominent problem in QM today: the shortage of an educated workforce, the scarcity of aspiring students.

Double-slit interference and single-slit diffraction experiments on electrons

De Broglie proposed the matter wave in 1924. The de Broglie wave is neither a mechanical wave nor an electromagnetic wave and has a very short wavelength. The Davisson-Germer electron diffraction experiment performed in 1925 involved bombarding the surface of a nickel crystal with a narrow beam of electrons. When the accelerating voltage V was maintained at 54 V, the wavelength of the incident electron was λ=h/ <mml:math display="inline"> <mml:msqrt> <mml:mn>2</mml:mn> <mml:mi mathvariant="normal">m</mml:mi> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">V</mml:mi> </mml:msqrt> </mml:math> = 0.167 nm [Y. S. Chen and Z. Z. Li, College Physics (Tianjin University, Tianjin, 1999)] demonstrating the existence of the matter wave. We introduce a type of electron wave with a very long wavelength in this study that is different from the matter wave. For example, the wavelength of the electron wave can reach 0.43 mm in the double-slit interference of electrons. Experiments demonstrate that this long-wavelength electron wave can produce both double-slit interference and electron diffraction. A comparative analysis of matter and electron waves reveals the physical natures of these waves and wave‐particle duality.

Determinism In Quantum Slit-Experiments

A mathematical model for the slit experiments in the heart of quantum mechanics is developed to gain insight into quantum ‎theory. The proposed system-theoretical model is entirely based on commutative mathematics, i.e. convolution, and integral ‎transformations, and starts with spacetime functions with inherent energy-based cause and effect relations of the state-‎function Ѱ in the complex Hilbert space. The benefits of his approach are as 1-Invariance in time reversal. 2-Deterministic ‎result functions in the model in line with the outcome of slit experiments. 3- Separation of causality and cross-correlations of ‎attained states. 4- Disappearance of a posteriori probability of quantum states. 5- Quantum a priori fixed states after ‎causality interactions have ended, (even) when quanta are (light-years) separated. The model predicts the patterns in the ‎experiments with mathematical functions of the energy distributions. The quantum mechanical counterpart description of the ‎physical reality of slit experiments thus may be considered complete in A. Einstein’s definition. The patterns in double slit ‎experiments are found to be an effect of energy (amplitude-) modulation. An equivalent double-slit pattern can be retrieved ‎from an input modulated 1-slit experiment excluding interference interpretations. The system-theoretical model uses generic ‎properties of quanta and evolves into determinism in ‎quantum mechanics slit experiments. The mathematics in the model ‎handles beables by treatment ‎of momentum p in system theoretical I/O relations of the transformed functions and allows the ‎proposed description by the avoidance of a direct addressing of the individual quanta through variables. The following ‎method yields exact, non-probabilistic results.‎

Theatre Meets Quantum Physics: René Pollesch’s Theatre for the Age of Technoscience

This article looks closely at how the German director René Pollesch incorporates quantum physics into his theatrical practice. I argue that the double-slit experiment that Pollesch refers to in his play Probleme Probleme Probleme (2019) is key to understanding his non-representational theatre. I analyze the deep implications of this experiment for his theatre with respect to two aspects: (1) I highlight the fact that his interest in the writings of feminist and philosopher of science Donna Haraway is connected to a critique of representational theatre with its specific conceptualization of “the Human” as a Cartesian subject; and (2) in line with feminist and physicist Karen Barad, I discuss how the double-slit experiment, understood as a queer phenomenon, helps Pollesch rework central categories of drama and representational theatre. Subsequently, this allows me to conclude that Pollesch continues Bertolt Brecht’s project of a political “theatre for the scientific age” under new conditions. His theatre is a political theatre for the “technoscientific age” where “the Human” as opposed to its “Others” no longer exists. The term diffraction is key for understanding my analysis because it functions as an analytical tool that connects the aforementioned aspects. Moreover, it also describes my method of making visible the pattern that comes into being when Pollesch meets the double-slit experiment, or, more generally speaking, when theatre meets quantum physics.

Application of Optical Path Drawing Technology: The Light Intensity Problem of Double-Slit Interference

The wave nature of light has been widely demonstrated in a double-slit experiment, which has played a special role in physics teaching. When monochromatic light passes through the double-slit sheet, the diffraction and interference fringes can be observed in the far-field regime. The interference of light causes the beams passing through the two slits to interact with each other, but each slit still retains the diffraction characteristics of a single slit, so the result is a combination of diffraction and interference patterns.

Teaching Double-slit Experiment with Modular Optical Experimental Instruments

The Modular Optical Experimental Instruments (MOEI) are newly-designed laboratory demonstration tools which integrate a whole set of optical devices on a single board. The instructors can easily bring the MOEI to classrooms and demonstrate optical phenomena on projector screens. In order to investigate the impact of MOEI on the instruction of double-slit experiment, we investigated 134 undergraduate students with an open-ended experiment designing task. The Primary Trait Analysis (PTA) score suggested that students learning double-slit experiments with MOEI had better performance in selecting equipment and understanding the nature of science and showed more engineering thinking. The results also showed that students had a common misconception about the width of interference fringes, and MOEI was helpful to avoid it.

Ultrahigh-dynamic-range wavefront sensor based on absolute double-slit interferometry

This Letter reports a new, to the best of our knowledge, technique for the quality testing of steep optical samples by introducing an absolute interferometry method based on a double-slit interference experiment. We determine the quality of the sample with an ultrahigh-dynamic-range wavefront sensor by determining the deformation of the central fringe of the double-slit interferometer recorded for two different separations of the slits. The transmission function of the double slit is implemented on an amplitude spatial light modulator. Therefore, the slits’ location can be easily displaced over the entire area of the sample’s wavefront. We applied the proposed method on two samples: a microscope slide and a conventional ophthalmic lens, and maximum absolute phase variations of 0.33 and 26.7 rad were measured, respectively. Our estimation shows that an absolute phase variation of about 700 rad can be measured with this method.

Two-path interference in resonance-enhanced few-photon ionization of Li atoms

We investigate the resonance-enhanced few-photon ionization of atomic lithium by linearly polarized light whose frequency is tuned near the $2s\text{\ensuremath{-}}2p$ transition. Considering the direction of light polarization orthogonal to the quantization axis, the process can be viewed as an atomic ``double-slit experiment'' where the $2p$ states with magnetic quantum numbers ${m}_{\ensuremath{\ell}}=\ifmmode\pm\else\textpm\fi{}1$ act as the slits. In our experiment, we can virtually close one of the two slits by preparing lithium in one of the two circularly polarized $2p$ states before subjecting it to the ionizing radiation. This allows us to extract the interference term between the two pathways and obtain complex phase information on the final state. The experimental results show very good agreement with numerical solutions of the time-dependent Schr\"odinger equation. The validity of the two-slit model is also analyzed theoretically using a time-dependent perturbative approach.

Hiding the which-path information of photons

Which-path information of a quantum particle in interferometers is the key to infer the past of quantum particle. It arises many extensive discussions including quantum complementarity and path-visibility relation. The basic of these discussions are the description, detection and control of which-path information. In this article, we focus on the investigation of multidimensional which-path information in nested Mach-Zehnder interferometer. A general expression of which-path information is given and can be partially extracted by different detection method. Further analysis shows that the which-path information can be controlled by the phase differences and beam splitting ratios between the arms of nested Mach-Zehnder interferometer. Moreover, a new which-path information elimination phenomenon has been predicted and demonstrated experimentally. Our work can help to understand the physics of quantum particles, potentially apply to quantum information process and quantum metrology.

Incompleteness of Wave Interpretations of Double Slit and Grating Experiments

Incompleteness of Wave Interpretations of Double Slit and Grating Experiments

Evaluation of twisted Gaussian Schell model beams produced with phase randomized coherent fields

The twisted Gaussian Schell Model describes a family of partially coherent beams that present several interesting characteristics, and as such have attracted attention in classical and quantum optics. Recent techniques have been demonstrated to synthesize these beams from a coherent source using a discrete set of ‘pseudo-modes’, where the phase of each mode is randomized so that they are mutually incoherent. Here we investigate this technique and evaluate the resulting beam parameters, such as divergence, coherence length and twist phase. We show that for a finite set of modes there is also some residual coherence, which can have an observable effect. A theoretical model is developed for the output field that includes residual coherence and agrees very well with experimental data. In addition, we demonstrate a simple method to measure the twist phase using double slit interference.

Analysis of single-photon self-interference in Young’s double-slit experiments

For centuries Young’s double-slit interference continues to be a hot discussion subject about whether light is waves or particles. This work unravels the self-interference parados, and sheds light on such a concept that assumes a photon can split, self-interfere, and recombine. This work elucidates how coherent photons from a laser source could produce a double-slit interference pattern without the hypothesis of unphysical splitting and recombination of a single photon. Unlike the conventional single wave-function description for the whole ensemble of particles, we develop a pilot-wave trajectory approach to track every photon’s wave-packet propagation and calculate the evolution of the interference intensity in time. We demonstrate how wave packets and phase coherence affect the interference pattern. To resolve the century-old self-interference paradox, we show that such an hypothesis is unnecessary, and the illusion is due to the long coherence length of laser photons and overlaps of delocalized light wave packets.

Fifteen years of quantum optics, quantum information, and nano-optics educational facility at the Institute of Optics, University of Rochester

The quantum optics/quantum information and nano-optics educational laboratory facility (QNOL) at the University of Rochester (UR) is located within three rooms of the Institute of Optics with a total area of 587 ft2. It has been used for teaching a 4-credit-hour QNOL class annually for 15 years. Four teaching labs were prepared on the generation and characterization of entangled and single (antibunched) photons demonstrating the laws of quantum mechanics: (1) entanglement and Bell’s inequalities, (2) single-photon interference (Young’s double slit experiment and Mach–Zehnder interferometer), (3) single-photon source I: confocal fluorescence microscopy of single nanoemitters, and (4) single-photon source II: a Hanbury Brown and Twiss setup, fluorescence antibunching. Further, based on QNOL, 1.5 to 3 h sturdy quantum “mini-labs” were developed and introduced into the required classes such that all optics students at the UR had experience with quantum labs. Monroe Community College (MCC) students participated in two mini-labs at the UR. Since 2006 to spring 2022, a total of ~850 students have utilized the labs for lab report submission (including 144 MCC students) and more than 250 students have used them for lab demonstrations. In addition, UR freshman research projects have become a very important educational activity in this facility. All developed materials and students’ reports are available at http://www.optics.rochester.edu/workgroups/lukishova/QuantumOpticsLab/. We present a description of sturdy, universally accessible experiments that can be introduced into either a separate advanced class or into classes with a large number of students. Assessment methods, evaluation of students’ knowledge, and their attitude toward their career in quantum information are discussed.

A diffraction experiment at the near field: the homemade Talbot effect

Diffraction refers to a kind of optical phenomena which occurs when light approaches an element (object or aperture) whose features are in the range of the illuminating wavelength (small apertures, sharp edges). It can be explained by means of the undulatory nature of light or also geometrically by using simple ray optics. Diffraction phenomena are impressive and not intuitive, so it makes them very interesting to bring examples to the classroom. The most popular diffraction experiments show effects in Fraunhofer regime, that is to be said, far from the diffractive object. Common examples are the single or double slit experiments. In this manuscript, we propose and show a less common diffractive effect that occurs in the Fresnel regime, near to the diffractive object. It is the Talbot effect or self-imaging phenomenon, which appears by illuminating a diffraction grating with a collimated monochromatic beam. It consists of the apparition of replicas (self-images) of the grating intensity pattern at periodic distances, multiples of the so-called Talbot distance. We show how this effect may be shown into the classroom with cheap and easy to find elements. In addition, we take advantage of its dependence on the coherence degree of the source to introduce the concept of optical coherence and show its effect on the contrast of the Talbot self-images. These experiments could be appropriate for undergraduate students or introductory physics courses.

Simulation of Afshar’s Double Slit Experiment

Shahriar S. Afshar claimed that his 2007 modified version of the double-slit experiment violates complementarity [1]. He makes two modifications to the standard double-slit experiment. First, he adds a wire grid that is placed in between the slits and the screen at locations of interference minima. The second modification is to place a converging lens just after the wire grid. The idea is that the wire grid implies the existence of interference minima(wave-like behavior), while the lens can simultaneously obtain which-way information (particle-like behavior). More recently, John G. Cramer [2] argued that the experiment bolstered the Transactional Interpretation of Quantum mechanics (TIQM). His argument scrutinizes Bohr's complementarity in favor of TIQM. We analyze this experiment by simulation using the path integral formulation of quantum mechanics [3] and find that it agrees with the wave particle duality relation given by Englert, Greenberg and Yasin (E-G-Y) [4, 5]. We conclude that the use of Afshar's experiment to provide a testbed for quantum mechanical interpretations is limited.

On the wave nature of particles

The main goal of the present article is to elucidate the wave-particle duality problem by giving an unambiguous mathematical expression of the origin of the wave nature of particles. It is indicated that the wave nature of particles is originated from the multidimensional universe approach and under the one-dimensional universe assumption the wave nature vanishes. The one-dimensional universe assumption also gives a deterministic explanation for the double-slit experiment and answers how a single electron can interfere with itself. The locality paradox is also discussed. It is demonstrated that the same principle shows how a local measurement can determine the state of a distant system. The theoretical framework presented here may help us to understand various quantum physics phenomena. i.e., the superposition principle, wave function collapse, and entanglement.

Quantum indistinguishability by path identity and with undetected photons

The double-slit experiment manifests the duality between wave interference and the distinguishability of paths taken by a particle though an apparatus. This article reviews advanced developments of these concepts with pairs of particles, starting with experiments on quantum foundations with photon pairs in the 1990s. These experiments now form the basis for applications in quantum information as well as for spatial imaging and spectroscopy that is performed without ever detecting the photons that interacted with the object.

Goldstone States as Non-Local Hidden Variables

We consider the theory of spinor fields in polar form, where the spinorial true degrees of freedom are isolated from their Goldstone states, and we show that these carry information about the frames which is not related to gravitation, so that their propagation is not restricted to be either causal or local: we use them to build a model of entangled spins where a singlet possesses a uniform rotation that can be made to collapse for both states simultaneously regardless their spatial distance. Models of entangled polarizations with similar properties are also sketched. An analogy with the double-slit experiment is also presented. General comments on features of Goldstone states are given.

Nondipole Time Delay and Double-Slit Interference in Tunneling Ionization.

Recently two-center interference in single-photon molecular ionization was employed to observe a zeptosecond time delay due to the photon propagation of the internuclear distance in a molecule [Grundmann etal., Science 370, 339 (2020)SCIEAS0036-807510.1126/science.abb9318]. We investigate the possibility of a comparable nondipole time delay in tunneling ionization and decode the emerged time delay signal. With the here newly developed Coulomb-corrected nondipole molecular strong-field approximation, we derive and analyze the photoelectron momentum distribution, the signature of nondipole effects, and the role of the degeneracy of the molecular orbitals. We show that the ejected electron momentum shifts and interference fringes efficiently imprint both the molecule structure and laser parameters. The corresponding nondipole time delay value significantly deviates from that in single-photon ionization. In particular, when the two-center interference in the molecule is destructive, the time delay is independent of the bond length. We also identify the double-slit interference in tunneling ionization of atoms with nonzero angular momentum via a nondipole momentum shift.

Inexpensive Single and Double Slits Using a Fine-Toothed Comb

For single-slit diffraction and double-slit interference experiments, commercially made slits can be the most expensive parts, especially since the prices of laser pointers have become very low. One option is to use a razor blade to cut slits in either paint or electrical tape on microscope slides. However, this takes practice, and there is some risk of injury, so it may not be reasonable to expect students to make their own slits in this way. Also, measuring the width and the separation of the slits produced requires a microscope. A simple, inexpensive alternative is to use the gaps of a fine-toothed comb as slits.