Double-slit Interference Pattern Research Articles

Time-resolved double-slit interference pattern measurement with entangled photons.

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.

Psychophysical interactions with a double-slit interference pattern

Previously reported experiments suggested that interference patterns generated by a double-slit optical system were perturbed by a psychophysical (i.e., mind-matter) interaction. Three new experiments were conducted to further investigate this phenomenon. The first study con- sisted of 50 half-hour test sessions where participants concentrated their attention-toward or -away from a double-slit system located 3 m away. The spectral magnitude and phase associated with the double-slit component of the interference pattern were compared between the two attention condi- tions, and the combined results provided evidence for an interaction (effect size ¼� 0.73 6 0.14, p ¼ 2.4 � 10 � 7 ). One hundred control sessions using the same equipment, protocol and analysis, but without participants present, showed no effect (effect size ¼ 0.04 6 0.10, p ¼ 0.71). A Fraunhofer diffraction model was used to explore various interpretations of this outcome. This analysis suggested that the distribution of light between the two slits and the horizontal stability of the laser beam were the principle components of the optical system that were perturbed. The sec- ond experiment used a duplicate double-slit system and similar test protocol, but it was conducted over the Internet by streaming data to participants' web browsers. Some 685 people from six conti- nents contributed 2089 experimental sessions. Results were similar to those observed in the first experiment, but smaller in magnitude (effect size ¼� 0.09 6 0.02, p ¼ 2.6 � 10 � 6 ). Data from 2303 control sessions, conducted automatically every 2 h using the same equipment but without observ- ers showed no effect (effect size ¼� 0.01 6 0.02, p ¼ 0.61). Distance between participants and the optical system, ranging from 1 km to 18,000 km, showed no correlation with experimental effect size. The third experiment used a newly designed double-slit system, a revised test protocol, and a simpler method of statistical analysis. Twenty sessions contributed by 10 participants successfully replicated the interaction effect observed in the first two studies (effect size ¼� 0.62 6 0.22, p ¼ 0.006). V C 2013 Physics Essays Publication .( http://dx.doi.org/10.4006/0836-1398-26.4.553) Resume´: Des experiences realisees precedemment suggerent que des franges d'interferences generees par un systeme de double fente optique peuvent etre perturbees par des interactions psycho-physiques (c'est-a `-dire des interactions entre conscience et matiere). Trois nouvelles expe ´- riences ont emenees pour etudier ce phenomene. Dans la premiere e au cours de 50 seances d'une demi heure chacune, des participants ont concentreleurs attentions soit pour influencer un systeme de double fente situee a` 3 m de distance, soit pour ignorer ce meme systeme. L'ampleur et la phase spectrale associee aux franges d'interference ont ecompares entre les deux conditions de focalisation de l'attention, et les resultats combines sont compatibles avec l'hypothese d'une inter- action entre conscience et matiere (taille d'effet ¼� 0.73 6 0.14, p ¼ 2.4 � 10 � 7 ). De plus, l'effet n'est pas present quand la meme analyse est effectuee sur cents sessions controles utilisant le meme equipement et le meme protocole, mais fonctionnant en l'absence de participants (taille d'effet ¼ 0.04 6 0.10, p ¼ 0.71). Un modele de diffraction de Fraunhofer utilisepour explorer dif- ferentes interpretations de ce resultat suggere que la distribution de la lumiere entre les deux fentes et la stabilitehorizontale du faisceau laser sont les principaux composants du systeme optique qui ont eperturbes. La seconde experience utilise un systeme de double fente et un protocole de test similaire, mais elle a etemenee sur Internet en envoyant en temps reel les donnees du systeme de double fente aux navigateurs Web des participants. 685 personnes provenant de six continents ont contribue ´ 2089 sessions experimentales. Les resultats sont similaires ala premiere experience mais la taille d'effet est de plus faible amplitude (taille d'effet ¼� 0.09 6 0.02, p ¼ 2.6 � 10 � 6 ). Les don- nees de 2303 sessions de controle, realiseautomatiquement toutes les deux heures en utilisant le meme e mais sans observateurs n'ont montreaucun effet (taille d'effet ¼� 0.01 6 0.02, p ¼ 0.61). La distance entre les participants et le systeme optique, qui va de 1 km a ` 18,000 km, n'est pas correlee avec la taille de l'effet experimental. La troisieme experience utilise un systeme

Zero-range-potential model for strong-field molecular processes: Dynamic polarizability and photodetachment cross section

We develop a general theoretical framework for the analytical description of the interaction of a model diatomic molecular system with an intense, arbitrarily polarized monochromatic laser field. The model molecule comprises an electron in the field of two zero-range potentials separated by the internuclear distance. This model has an exact analytical solution within the theoretical framework of the quasistationary quasienergy (Floquet) approach. In addition to the development of this general framework, we also present a detailed analysis of the weak-field limit, within which we obtain both the frequency-dependent polarizability and the angle-resolved photodetachment cross section for the model system. These fundamental properties are analyzed for both homonuclear and heteronuclear molecular systems in a linearly polarized laser field, for both ground and excited electronic states, and for arbitrary orientation of the molecular axis relative to the polarization vector of the laser field. The analytical expressions for the polarizability and angle-resolved photoelectron spectra exhibit characteristic double-slit interference patterns, allowing one to study their dependence on the parameters of the problem beyond the level of the Born approximation.

Quantum measurements are physical processes. Comment on "Consciousness and the double-slit interference pattern: Six experiments," by Dean Radin et al. [Phys. Essays 25, 157 (2012)

The validity of the assertion that some recent double-slit interference experiments, conducted by Radin et al., would have tested the possible role of the experimenter's mind in the collapse of the quantum wave function, is questioned. It is emphasized that quantum mechanics doesn't need any psychophysical ingredient to explain the measurement processes, and therefore parapsychologists shouldn't resort to the latter to support the possibility of psychokinesis, but search for more convincing explanations.

Consciousness and the double-slit interference pattern: Six experiments

A double-slit optical system was used to test the possible role of consciousness in the collapse of the quantum wavefunction. The ratio of the interference pattern's double-slit spectral power to its single-slit spectral power was predicted to decrease when attention was focused toward the double slit as compared to away from it. Each test session consisted of 40 counterbalanced attention-toward and attention-away epochs, where each epoch lasted between 15 and 30 s. Data contributed by 137 people in six experiments, involving a total of 250 test sessions, indicate that on average the spectral ratio decreased as predicted (z=-4:36, p=6·10 -6 ). Another 250 control sessions conducted without observers present tested hardware, software, and analytical procedures for potential artifacts; none were identified (z=0:43, p=0:67). Variables including temperature, vibration, and signal drift were also tested, and no spurious influences were identified. By contrast, factors associated with consciousness, such as meditation experience, electrocortical markers of focused attention, and psychological factors including openness and absorption, significantly correlated in predicted ways with perturbations in the double-slit interference pattern. The results appear to be consistent with a consciousness-related interpretation of the quantum measurement problem. 2012 Physics Essays Publication. (DOI: 10.4006/0836-1398-25.2.157) R ´ esum ´

‘Quantum interference with slits’ revisited

Marcella has presented a straightforward technique employing the Dirac formalism to calculate single- and double-slit interference patterns. He claims that no reference is made to classical optics or scattering theory and that his method therefore provides a purely quantum mechanical description of these experiments. He also presents his calculation as if no approximations are employed. We show that he implicitly makes the same approximations found in classical treatments of interference and that no new physics has been introduced. At the same time, some of the quantum mechanical arguments Marcella gives are, at best, misleading.

A matterless double slit

Double-slits provide incoming photons with a choice. Those that survive the passage have chosen from two possible paths which interfere to distribute them in a wave-like manner. Such wave-particle duality continues to be challenged and investigated in a broad range of disciplines with electrons, neutrons, helium atoms, C60 fullerenes, Bose-Einstein condensates and biological molecules. All variants have hitherto involved material constituents. We present a matterless double-slit scenario in which photons generated from virtual electron-positron pair annihilation in head-on collisions of a probe laser field with two ultra-intense laser beams form a double-slit interference pattern. Such electromagnetic fields are predicted to induce material-like behaviour in the vacuum, supporting elastic scattering between photons. Our double-slit scenario presents on the one hand a realisable method to observe photon-photon scattering, and demonstrates on the other, the possibility of both controlling light with light and non-locally investigating features of the quantum vacuum's structure.

Young-type interference in collisions between helium and molecular hydrogen ions

The dissociative electron transfer from He into 10 keV H+2 was measured in a kinematically complete experiment. For electron transfer into the dissociative b3Σ+u state of H2 we find a striking double slit interference pattern in the transverse momentum transfer which we can modify by selecting different internuclear distances of the hydrogen molecule. Compared to an optical double slit, interference minima and maxima are interchanged.

Young-Type Interference in Collisions between Hydrogen Molecular Ions and Helium

The dissociative electron transfer from He into 10 keV H2+ was measured in a kinematically complete experiment by using the cold target recoil ion momentum spectroscopy imaging technique in combination with a highly resolving molecular fragment imaging technique. The electron transfer into the dissociative b(3)Sigma+_(u) state of H2 could be selected by kinematic conditions. We find a striking double slit interference pattern in the transverse momentum transfer which we can modify by selecting different internuclear distances. Compared to an optical double slit, interference minima and maxima are interchanged. The latter is the result of a phase shift in the electronic part of the wave function.

Double-Slit Interference Pattern from Single-Slit Screen and Its Gravitational Analogues

The double slit experiment (DSE) is known as an important cornerstone in the foundations of physical theories such as Quantum Mechanics and Special Relativity. A large number of different variants of it were designed and performed over the years. We perform and discuss here a new version with the somewhat unexpected results of obtaining interference pattern from single-slit screen. We show using either the Brill’s version of the canonical formulation of general relativity or the linearized version of it that one may find corresponding and analogous situations in the framework of general relativity.

Varying shapes of experimental double-slit interference patterns for light, and a model of particle-modified interference patterns

Interference patterns from laser-illuminated double slits were scanned and accumulated for the cases of relatively dim, medium and relatively bright illumination. Detailed analyses were made of the pattern shapes for a large number of data runs. Patterns accumulated from dim light fit the shape of the wave theory patterns well, supporting the quantum concept of gradual accumulation of single photon events. However, the envelope shapes for brighter light did not adequately match those of the wave theory (or those from dim light), in that the bright light patterns had too great an intensity in the bright areas, relative to the dimmer areas in those patterns. These pattern shapes resembled a wave theory pattern squared, or taken to a higher power. The shapes appear to have been the results of the particular method of pulse detection and pulse level discrimination used, which favoured the larger pulse sizes. A model based upon multiple photon detection within each output pulse was developed, using particle statistics combined with wave theory probabilities. The predicted interference patterns from this model fit the experimental results well, providing support for the model. This experiment displays an interesting combination of wave and particle effects, supporting duality for light, in that the transmission of light corresponds to the predictions of probability waves, closely akin to classical optical wave theory, and the detection of light involves particle statistics, supporting the quantum nature of photon detection.

Classical Electromagnetism and the Aharonov–Bohm Phase Shift

Although there is good experimental evidence for the Aharonov–Bohm phase shift occurring when a solenoid is placed between the beams forming a double-slit electron interference pattern, there has been very little analysis of the relevant classical electromagnetic forces. These forces between a point charge and a solenoid involve subtle relativistic effects of order v 2 /c 2 analogous to those discussed by Coleman and Van Vleck in their treatment of the Shockley–James paradox. In this article we show that a treatment exactly analogous to that given by Coleman and Van Vleck predicts classical electromagnetic forces which provide the basis for the Aharonov–Bohm phase shift. The magnetic force on the solenoid due to the passing charge leads to a displacement of the solenoid center of energy which must be balanced by the displacement of the passing charge. This classical displacement of the passing charge is exactly what is required to account for the Aharonov–Bohm phase shift. Also, we discuss a magnetic moment model which appears frequently in the literature and note that although the model provides conservation of linear momentum, it does not satisfy the general requirements for relativistic theories. We give an example suggesting that the new equation of motion for a magnetic moment proposed by Aharonov, Pearle, and Vaidman based upon the hidden momentum of the magnetic moment is completely inappropriate. Finally, we emphasize that the Aharonov–Casher phase shift is also explained by classical electromagnetic forces exactly parallel to those explaining the Aharonov–Bohm phase shift.

The Effect of Path Observation on Quantum Interference Pattern

A Gedankenexperiment is presented on the effect of imperfect detection of the electron path on the double slit interference pattern. Incorporating into our quantum system the detectors for the electron path and the observer who recognizes the response of the detectors, one can decompose the ensemble of electrons with their spots on the film into three subensembles according as the upper, lower or neither detector responds. Only the third ensemble shows the interference pattern. Negative result measurement is included as a special case. This Gedankenexperiment allows one to put the argument of Bohr's complementarity of the wave/particle duality on a quantitative basis. The realization of the experiment is well within the high technology of the present day.