Double-slit Research Articles

Observations of Cross-Double-Slit Experiments

Young’s double-slit experiment had been performed over 200 years ago. Two- dimension cross-double-slit has been proposed recently. We report observations of two-dimension-cross-interference patterns created by two-dimension cross-double-slit apparatuses.

Interaction of wave-driven particles with slit structures.

Just over a decade ago Couder and Fort [Phys. Rev. Lett. 97, 154101 (2006)PRLTAO0031-900710.1103/PhysRevLett.97.154101] published a provocative paper suggesting that a classical system might be able to simulate the truly fundamental quantum mechanical single- and double-slit experiment. The system they investigated was that of an oil droplet walking on a vibrated oil surface. Their results have since been challenged by Andersen etal. [Phys. Rev. E 92, 013006 (2015)PLEEE81539-375510.1103/PhysRevE.92.013006] by pointing to insufficient statistical support and a lack of experimental control over critical parameters. Here we show that the randomness in the original experiment is an artifact of lack of control. We present experimental data from an extensive scan of the parameter space of the system including the use of different size slits and tight control of critical parameters. For the single-slit we find very diverse samples of interference-like patterns but all causal by nature. This also holds for the double-slit. However, an extra interference effect appears here. The origin of this is investigated by blocking either the inlet or the outlet of one slit. Hereby we show that the extra interference is solely due to back-scatter of the associated wave field from the outlet of the slit not passed by the droplet. Recently Pucci etal. [J. Fluid Mech. 835, 1136 (2018)JFLSA70022-112010.1017/jfm.2017.790] using a much broader slit also showed that the classical system is basically causal. They, too, observed the extra interference effect for the double-slit. However, the reason behind was not determined. Moreover they claimed the existence of a chaotic regime just below the cri- tical acceleration for spontaneous generation of Faraday surface waves. Our measurements do not support the validity of this claim. However, the drop dynamics turns out to have an interesting multifaceted interaction with the slit structure.

Wave-particle-duality relations based on entropic bounds for which-way information

We present wave-particle duality relations involving the relative entropy coherence measure, which plays a prominent role in the resource theory of coherence. The main input in these relations is an entropic bound for the which-way information, which we derive in this letter. We show that this latter crucially depends on the choice of the measurement strategy to obtain the path information. In particular, we present results for two strategies: zero-error identification of the path-detector states, which never produces an error but sometimes fails to return a conclusive answer, and a mixed strategy where both errors and failure are allowed.

The classical double slit experiment–a study of the distribution of interference fringes formed on distant screens of varied shapes

The double slit experiment was the first demonstrative proof of the wave nature of light. It was expounded by the English physician-physicist Thomas Young in 1801 and it soon helped lay to rest the then raging Newton–Huygens debate on whether light consisted of a fast-moving stream of particles or a train of progressive waves in the ether medium. In the experiment, light is made to pass through two very narrow slits spaced closely apart. A screen placed on the other side captures a pattern of alternating bright and dark bands called fringes which are formed as a result of the phenomenon of interference. In prior work by the same author, it was shown that the conventional analysis of Young’s experiment that is used in many introductory physics textbooks, suffers from a number of limitations in regards to its ability to accurately predict the positions of these fringes on the distant screen. This was owing to the adoption of some needless and paradoxical assumptions to help simplify the geometry of the slit barrier-screen arrangement. In the new analysis however, all such approximations were discarded and a hyperbola theorem was forwarded which was then suitably applied to determine the exact fringe positions on screens of varied shapes (linear, semi-circular, semi-elliptical). This paper further builds on that work by laying down the mathematical framework necessary for counting fringes and then comparing their distributions on differently shaped screens, using MATLAB software package for numerical–graphical simulation. In addition, a pair of equivalent laws of proportionality are predicted that govern the distribution of fringes independent of the shape of the detection screen employed.

Demystifying the delayed-choice quantum eraser

The delayed-choice quantum eraser has long been a subject of controversy, and has been looked at as being incomprehensible to having retro-causal effect in time. Here the delayed-choice quantum eraser is theoretically analyzed using standard quantum mechanics. Employing a Mach–Zehnder interferometer, instead of a conventional two-slit interference, brings in surprising clarity. Some common mistakes in interpreting the experiment are pointed out. It is demonstrated that in the delayed mode there is no which-way information present after the particle is registered on the screen or the final detectors, contrary to popular belief. However, it is shown that another kind of path information is present even after the particle is registered in the final detectors. The registered particle can be used to predict the results of certain yet to be made measurements on the which-way detector. This novel correlation can be tested in a careful experiment. It is consequently argued that there is no big mystery in the experiment, and no retro-causal effect whatsoever.

Wave-particle duality using the Compton effect

Thought experiments based on the double-slit interferometer had a crucial role to develop ideas concerning the wave-particle duality and the Bohr's complementarity principle. Ideally, a slit with a sufficiently low mass recoils due to the passage of the photon. This motion denounces the path taken by the light and suppresses any attempt to observe an interference pattern. In real life, however, available which-way information in such a setup is significantly impaired by the typical magnitudes of photons and slits, making the verification of the effect almost impossible. Here, we extend this discussion by applying similar ideas to the Mach-Zehnder interferometer. That is, we study the consequences of the beam-splitter recoil, during the passage of the photon, over the interference pattern produced by the device. Unlike the double-slit experiment, this recoil can now be encoded in the wavelength of the photon itself, which, in principle, is more easily accessed. Fortuitously, the model used to describe the interaction between the idealized beam-splitter and the photon clearly indicates that an interferometer based on Compton's effect could be build to study wave-particle duality. We follow this hint, finding realistic experimental parameters needed to observe the trade-off between wave and corpuscular behaviors in such a modified interferometer.

Conceptual Remote Distance Measurement with a Double-Slit Interference

Distance measurement is crucial to astronomy. Here, we suggest a new conceptual method to measure the distance by using a local instrument. By engaging the double-slit interference and by considering the phase information of the light, the position of the intensity maximum is related to the distance of the source. Consequently, the precise measurement of the position can be used to measure the distance of the remote source.

Blind Witnesses Quench Quantum Interference without Transfer of Which-Path Information.

Quantum computation is often limited by environmentally-induced decoherence. We examine the loss of coherence for a two-branch quantum interference device in the presence of multiple witnesses, representing an idealized environment. Interference oscillations are visible in the output as the magnetic flux through the branches is varied. Quantum double-dot witnesses are field-coupled and symmetrically attached to each branch. The global system—device and witnesses—undergoes unitary time evolution with no increase in entropy. Witness states entangle with the device state, but for these blind witnesses, which-path information is not able to be transferred to the quantum state of witnesses—they cannot “see” or make a record of which branch is traversed. The system which-path information leaves no imprint on the environment. Yet, the presence of a multiplicity of witnesses rapidly quenches quantum interference.

The Diffracting Light in Contemporary Theatre

Light in theatre has long remained in a linear reflective relationship with performance and spectators, which is governed by the conceptual framework of dramatic theatre. It is subordinated to texts, representational, illusionary and atmospheric. The double-slit diffraction experiment reveals the paradoxical wave-particle duality property of light other than its linearity. The diffraction patterns exposed not only leads the way to quantum physics but also open up their potentialities in reimagining the conceptual frameworks of light and theatre. By re-turning to three original cross-disciplinary light-theatre-installation works through the concept and diffractive methodology proposed by Karen Barad, I examine the diffraction patterns created within and beyond the works to reconfigure the aesthetics of light in contemporary theatre. Light sets out from the concept of postdramatic theatre and its critical questioning of dramatic theatre to diffract and entangle with medicine, theatre, music, space, time, life, death, Cantonese opera, Hong Kong, world and spectators. Light destabilizes and diffracts the space-time of medicine-theatre, cut together-apart the infinite possibilities within a light-installation, troubles the space-time-matter and re-visit the entanglement of tradition-contemporaneity-fiction-reality-Hong Kong-world in a light-Cantonese opera performance. The on-going intra-actions within and beyond light in the three works re-turn and reconfigure the aesthetics of light, theatre and installation. They also call for the responsibility and response-ability of light and theatre inclusive of spectators, and the re-imagination of the ethico-political in the theatre-world.

Can students apply the concept of “which-path” information learned in the context of Mach–Zehnder interferometer to the double-slit experiment?

The ability to use concepts learned in one context to solve problems in a different context (i.e., transfer of learning) is often one of the major goals of physics instruction. After all, the ability to transfer learning from one context to another is a prerequisite to recognizing the applicability of compact physical laws to a multitude of contexts and is a hallmark of expertise in physics. The majority of the studies on transfer of learning in physics have focused on introductory students and it has often been found that introductory students have difficulty in effectively transferring their learning and applying what they learned in one situation to another situation. However, compared to advanced students, introductory students have significantly less prior relevant knowledge and skills, which may be crucial for promoting effective transfer. Here, we examine upper-level undergraduate and graduate students' ability to transfer their learning about the concept of “which-path” information and its relation to whether or not interference is observed from the context of the Mach Zehnder interferometer (MZI) to a new context of the double-slit experiment (DSE). Students worked through a tutorial on the MZI in which they learned to use the concept of which-path information to reason about interference of single photons when polarizers with various orientations are placed in one or both paths of the MZI. After working on the MZI tutorial, students were asked similar questions in the isomorphic context of the DSE before any instruction about the DSE and we examined the extent to which transfer of learning about which-path information occurred from the MZI to the DSE context. We find evidence suggesting that positive transfer of learning from the MZI to the DSE occurred despite the lack of an instructional intervention designed to help students recognize the similarity between the two contexts. The effectiveness of the MZI tutorial in promoting positive transfer of learning from one context to another in quantum mechanics sheds light on the expertise of the advanced physics students. Instructors of advanced physics courses can take advantage of the findings presented here, which show the difference between introductory and advanced physics students' expertise and ability to transfer from one context to another.

The heuristic model of energy propagation in free space, based on the detection of a current induced in a conductor inside a continuously covered conducting enclosure by an external radio frequency source

AbstractThe objective of this study is to propose a heuristic model of energy propagation due to an anomaly; electromagnetic (EM) field penetration into a continuously covered conducting enclosure (Faraday shield) from an external radio frequency source, violating the accepted model in the EM field theory. In this study, at an arbitrarily selected frequency, range of 26.965–1,800 MHz, of an external frequency source, an EM field inside the conducting enclosure was observed, contrary to expectations, which was followed by a systematic examination. Although no induced voltage could be expected inside the enclosure according to the classical theory, the experiment revealed a clear induced voltage inside, an attenuated induced voltage of −18.0 to −1.0 dB (for the range of frequencies 26.965–1,800 MHz) was observed. Hence, these results apparently contradict the established notion that an EM field cannot penetrate a Faraday shield. Rationalizing these observations and the results of the investigation leads to an alternative model to the existing models of energy propagation in free space. In this model, novel quantities named “I-Spin-energy” and “I-Spin-energy field” are defined to replace the concept of electric and magnetic fields in the classical EM theory. The proposed I-Spin-energy model is capable of explaining the unexpected presence of the EM field inside the Faraday shield as well as the induction of an alternating current in a conductor placed inside a Faraday shield along with other existing observations in physics such as those in famous Young’s double-slit experiment on interference of light, which provided the basis for the wave theory.

Squeezing and slowed quantum decoherence in the double-slit experiment

We study the slowing of the decoherence effect in the double-slit experiment by considering an initially correlated Gaussian state. The effects of the decoherence are included in a specific propagator which we use to obtain the density matrix at the detection screen. We calculate the uncertainties in the position and momentum for the density matrix as a function of the decoherence at the detection screen. We show that for a contractive initial state and specific times of propagation the state at the detection screen is squeezed in position in comparison with the standard Gaussian superposition. For this squeezed Gaussian superposition state, we observe that the fringe visibility is more robust to the decoherence in comparison with the standard Gaussian superposition. Then, we calculate the negativity of the Wigner function and study its behavior as a function of the decoherence and correlation parameters at the detection screen. We observe that the negativity decreases more slowly for the squeezed Gaussian superposition.

Otomatisasi Eksperimen Interferensi Tiga Celah

Automation of three slit interference experiments has been carried out. The light interference is an interesting phenomenon to observe. The observation of the three-slit interference pattern uses a light sensor that is connected to the computer through the interface. Light intensity data will be directly recorded into the computer and displayed in the form of graphs of the light intensity versus time. To measure the pattern of the formed dark light, the light sensor is placed on a linear drive system. This drive system will move the sensor to the left or right to record the intensity of the pattern of dark light. The purposes of this study are: 1) designing an automatic experiment to observe three slit interference patterns and 2) measuring the wavelength of the light source, He-Ne laser, used in the experiment. From the experiment, we find that the wavelength of He-Ne laser is nm.

Quantum Erasure Using Entangled Surface Acoustic Phonons

Using the deterministic, on-demand generation of two entangled phonons, we demonstrate a quantum eraser protocol in a phononic interferometer where the which-path information can be heralded during the interference process. Omitting the heralding step yields a clear interference pattern in the interfering half-quanta pathways; including the heralding step suppresses this pattern. If we erase the heralded information after the interference has been measured, the interference pattern is recovered, thereby implementing a delayed-choice quantum erasure. The test is implemented using a closed surface-acoustic-wave communication channel into which one superconducting qubit can emit itinerant phonons that the same or a second qubit can later re-capture. If the first qubit releases only half of a phonon, the system follows a superposition of paths during the phonon propagation: either an itinerant phonon is in the channel, or the first qubit remains in its excited state. These two paths are made to constructively or destructively interfere by changing the relative phase of the two intermediate states, resulting in a phase-dependent modulation of the first qubit's final state, following interaction with the half-phonon. A heralding mechanism is added to this construct, entangling a heralding phonon with the signalling phonon. The first qubit emits a phonon herald conditioned on the qubit being in its excited state, with no signaling phonon, and the second qubit catches this heralding phonon, storing which-path information which can either be read out, destroying the signaling phonon's self-interference, or erased.

Double-slit interference with a caliper

The implementation of a simple double-slit for light interference experiments by using just three off-the-shelf, non-optical components is described. Thanks to the simplicity of the assemblage, the distance between the slits and slit width can be easily modified. The device can be used in teaching laboratories for quantitative experiments, as well as in demonstration classes.

Light interference pattern measurements from automated low-cost Young’s double-slit experiments

Light interference pattern measurements from automated low-cost Young’s double-slit experiments

Psychological ‘double-slit experiment’ in decision making: Quantum versus classical

This paper is devoted to justification of the application of quantum probability theory to problems of cognition, psychology, and decision making. Such applications are heavily based on quantum-like representation of interference of events that is formalized with complex probability amplitudes (“mental wave functions”) and the Born rule for calculation of probability. In this paper, we present universal mathematical formalization of interference of events based on the calculus of intensities of interacting processes. Generally, this formalization leads to the nonlinear law of superposition of complex probability amplitudes with quantum linear superposition as a special important case. For intensities characterized by discrete occurrence of events, the formula for interference of intensities is transferred into the quantum-like formula for interference of probabilities. We illustrate the formalism by simple examples of possible applications of the calculus of intensities of processes to decision making and economics. We show that in special cases the classical (Kolmogorov) probabilistic model can give the same results as the quantum rule of summation of probabilities.

Observation of attosecond electron dynamics in the photoelectron momentum distribution of atoms using few-cycle laser pulses

The method of time-resolved measurement with ultrashort laser pulses is vital to the development of attosecond science. Pump-probe measurements using a train of attosecond pulses in combination with a near-infrared (NIR) multicycle driving laser have been successful in capturing the intercycle electron dynamics which repeats every optical cycle and leads to above-threshold ionization (ATI) spectra in the frequency domain. In this work, we study the effect of a carrier-envelope phase (CEP) in a few-cycle ($l6$ fs) NIR laser pulse on the photoelectron momentum distribution (PMD) of a hydrogen atom and show that interference patterns in a PMD change dramatically with CEPs in the few-cycle regime. When the few-cycle driving laser pulse has a sine shape, the double-slit interference with characteristic modulation of ATI peaks dominates the PMD. On the other hand, when the driving pulse has a cosine shape, the holographical interference featured by a spider-like pattern is isolated. Our results suggest that the CEP-stable few-cycle laser pulses can be used to identify different types of intracycle interference structures in a PMD which reveal the underlying subcycle electron dynamics on an attosecond timescale.

Double Helix Wave-Particle Structures of Photon and Charged Elementary Particles. The Equation of Motion of the Particle with Both Intrinsic Spin and Double Helix Structure has the Same form as the Schrodinger Equation

Photon and charged elementary particles have many commonalities like constant spin, duality, etc. The purpose of this paper is trying to find out why such particles have the commonalities and how to make the commonalities. The first part of this paper is to derive and prove that the photon is consisted of an energy packet and a closely connected circular polarized EM wave with much smaller energy. The energy packet is a thin piece of circular polarized EH field wrapped by a cylindrical side membrane with helical distributed . Double helix structure of field EH in the energy packet plus intrinsic speed c being proved makes almost all the basic properties of photon in the paper. The wave-particle properties in the structure of photon plays a roll together in the process of emission, absorption and interference. Such structure makes the photon to act as both a wave and a particle at the same time, not “exhibit different characters for different phenomenon”. It makes the dispute in the double slit experiment unnecessary. Charged elementary particles produced from a photon in the pair production will be proved in the paper it is split equally point to point from the photon. So the particles possess double helix structure of mass density and charge (or ). The helically distributed charge (or ) carries a circular polarized external E-field to move with the same velocity (a wave really). Of the charged elementary particle and of this E-wave will be proved to satisfy the de Broglie Relation here. It naturally leads to the differential equation of motion of such particles mathematically as same as the Schrodinger equation. Such differential equation of motion for the non-relativistic particles will be proved it is for the circular polarized structure and wave. Difference between helical (or ) and helical makes the charged elementary particles and photon distinguishable or undistinguishable by the magnetic B effect and to obey different statistics, F-D statistics or B-E statistics; and obey the Pauli Exclusion Principle or not. Since the spin direction of the photon and charged elementary particles are decided by the direction of helical structure, anyone of these particles can only possess a definite direction of spin, so the entanglement is like a pair of gloves disregard of how far the distance between them. Because a particle cannot locate at two positions or possess two different magnitudes of energy at the same time, (otherwise, the particle will split or move with different speed simultaneously), the particle itself can take only one basis state (e.g. at a point in the interference pattern or in an eigen state of the atom or molecule) any time. Therefore, the idea like wave function collapse, electron cloud and both alive and dead Schrodinger cat are no longer necessary. At last, it is a proof that there is a particular relativistic property of the charged elementary particles in the equal energy process. It will affect the physical and chemical process in the atom and molecule.

Atomic test of higher-order interference

Canonical quantum formalism predicts that the interference pattern registered in multi-slit experiments should be a simple combination of patterns observed in two-slit experiments. This has been linked to the validity of Born's rule and verified in precise experiments with photons as well as molecules via nuclear magnetic resonance. Due to the expected universal validity of Born rule, it is instructive to conduct similar tests with yet other physical systems. Here we discuss analogs of triple-slit experiment using atoms allowing tripod energy level configuration, as realisable e.g. with alkaline-earth-like atoms. We cover all the stages of the setup including various ways of implementing analogs of slit blockers. The precision of the final setup is estimated and offers improvement over the previous experiments.