The double-slit experiment has been a cornerstone in understanding modern-day physics.From interference of photons, and electrons to Bose-Einstein condensates, it has been the most fundamental measure of the quantum nature of a particle.In this work, it has been tried to make this experiment more accessible by using a phone camera and readily available apparatus.A smartphone camera uses a CMOS sensor.This is a sensitive sensor and in principle can also be used to observe ionized electrons produced by gamma rays.If a double slit is placed over a smartphone camera, an interference pattern can be observed by using the proper thresholding and image processing algorithms.In this work, an experiment has been designed that shows this most fundamental quantum phenomenon through a normal phone camera.
The double-slit experiment has been a cornerstone in understanding modern-day physics.From interference of photons, and electrons to Bose-Einstein condensates, it has been the most fundamental measure of the quantum nature of a particle.In this work, it has been tried to make this experiment more accessible by using a phone camera and readily available apparatus.A smartphone camera uses a CMOS sensor.This is a sensitive sensor and in principle can also be used to observe ionized electrons produced by gamma rays.If a double slit is placed over a smartphone camera, an interference pattern can be observed by using the proper thresholding and image processing algorithms.In this work, an experiment has been designed that shows this most fundamental quantum phenomenon through a normal phone camera.
This work proposes a novel variation of the double-slit experiment in which two different types of quantum particles — for example, electrons and photons — pass simultaneously through a shared double-slit apparatus. The primary objective is to test the hypothesis that the act of measurement may not only collapse the wave function of the observed particle, but could also influence the interference pattern of an unmeasured, co-propagating particle of a different type. In the proposed configuration, photons and electrons are emitted in synchrony and directed through the same set of slits. Immediately after the slits, a path-detecting measurement apparatus is applied only to one type of particle (e.g., photons), while the interference pattern of the other type (e.g., electrons) is recorded on a distant screen. The experiment is designed to explore whether the destruction of coherence through measurement is strictly local, or whether it can propagate to other particles through a shared medium, entangled fields, or an unknown interaction. If the unmeasured particle continues to display interference, this would support the locality of measurement effects. Conversely, if interference vanishes for both, it could indicate a more global or field-level decoherence process. This investigation aims to contribute new insights into the nature of quantum measurement, the role of observation, and the interdependence of coherent systems involving distinct particle species.
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.
Commercially available cameras do not have a low-enough dark noise to directly capture double-slit interference at the single photon level. In this work, camera noise levels are significantly reduced by activating the camera only when the presence of a photon has been detected by the independent detection of a time-correlated photon produced via parametric down-conversion. This triggering scheme provides the improvement required for direct video imaging of Young's double-slit experiment with single photons, allowing clarified versions of this foundational demonstration. We present video data of the evolving interference patterns. Also, we introduce variations on this experiment aimed at promoting discussion of the role spatial coherence plays in such a measurement, emphasizing complementary aspects of single-photon measurement and highlighting the roles of transverse position and momentum correlations between down-converted photons, including examples of “ghost” imaging and diffraction.
We report observations of Cross-Double-Slit Experiment and Which-Path-Cross-Double-Slit experiment. Cross-Double-Slit apparatus contains two double-slit, where first double-slit is perpendicular to second double-slit. The first double-slit and the second double-slit generate not only their own interference pattern perpendicular to each other, but also generate “Cross-interference-patterns”. When we do which-way experiment with one of two double-slit, say first double-slit, then its interference pattern disappeared, i.e., photons behave as particles; but the second double-slit’s interference pattern and the cross-interference-pattern still exist; which implies an significant phenomenon that in the same experiment, photons behave as both wave and particle, which is first time caught on film. Thus we suggest to re-study wave-particle duality, which is the basic mystery of quantum mechanics. We postulate that the particle nature of photons is intrinsic; while the wave-like of photons is manifest-behavior.
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.
Full text: We present two experiments on single- and two-particle interference. In the single-photon interference experiment, photons from a spontaneous parametric down-conversion (SPDC) source are send through a double slit. An interference pattern is built up frame by frame from shots obtained with an EMCCD camera behind the slit. Each frame contains on average less than one photon, thus demonstrating true single-photon sensitivity of the camera. The build-up of the interference pattern nicely demonstrates the concept of wave-particle duality. In a next step, we describe the Heisenberg's lens experiment and present the conditions required to analyse and investigate the spatial correlations of momentum entangled photons produced by SPDC. The occurrence of double-slit interference now depends on the experimental arrangement for the second photon of the pair, for example: interference can only occur if the second photon is also passing a double slit. We present an analysis of such a double-double-slit experiment. (author)