We study the quantum-to-classical transition induced by the loss of coherence in the double-slit experiment with large molecules. We introduce the effects of loss of coherence by considering a propagator that includes such effects. We calculate the fringe visibility and the volume of the negative part of the Wigner function and observe that these quantities decrease when the effects of loss of coherence increase.
We study the quantum-to-classical transition induced by the loss of coherence in the double-slit experiment with large molecules. We introduce the effects of loss of coherence by considering a propagator that includes such effects. We calculate the fringe visibility and the volume of the negative part of the Wigner function and observe that these quantities decrease when the effects of loss of coherence increase.
Based on the Threshold Chain Reaction Hypothesis, we construct a complex field equation with a nonlinear threshold term and perform numerical simulations of electron double-slit interference. Results show: when the threshold parameter is extremely high (never triggered), the equation reduces to the linear Schrödinger equation, faithfully reproducing standard quantum interference fringes; as the threshold decreases, fringe visibility declines continuously; at very low thresholds, interference vanishes completely, leaving only the single-slit diffraction envelope. This model provides a quantitatively tunable quantum-classical transition mechanism without requiring environmental coupling, offering a new perspective on the quantum measurement problem.
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.
The double slit experiment provides a classic example of both interference and the effect of observation in quantum physics. When particles are sent individually through a pair of slits, a wave-like interference pattern develops, but no such interference is found when one observes which "path" the particles take. We present a model of interference, dephasing, and measurement-induced decoherence in a one-dimensional version of the double-slit experiment. Using this model, we demonstrate how the loss of interference in the system is correlated with the information gain by the measuring apparatus/observer. In doing so, we give a modern account of measurement in this paradigmatic example of quantum physics that is accessible to students taking quantum mechanics at the graduate or senior undergraduate levels.
We study the loss of quantumness caused by time dilation [I. Pikovski, M. Zych, F. Costa, and \ifmmode \check{C}\else \v{C}\fi{}. Brukner, Nat. Phys. 11, 668 (2015)] for a Schr\"odinger cat state. We give a holistic view of the quantum to classical transition by comparing the dynamics of several nonclassicality indicators, such as the Wigner function interference fringe, the negativity of the Wigner function, the nonclassical depth, the Vogel criterion, and the Klyshko criterion. Our results show that only two of these indicators depend critically on the size of the cat, namely, on how macroscopic the superposition is. Finally we compare the gravitation-induced decoherence times to the typical decoherence times due to classical noise originating from the unavoidable statistical fluctuations in the characteristic parameters of the system [J. Trapani, M. Bina, S. Maniscalco, and M. G. A. Paris, Phys. Rev. A 91, 022113 (2015)]. We show that the experimental observation of decoherence due to time dilation imposes severe limitations on the allowed levels of classical noise in the experiments.
Abstract In certain analyses of quantum systems, it is common to disregard the dissipation effect and focus solely on decoherence. This is because decoherence typically occurs on a much shorter timescale compared to dissipation. However, in order to gain insight into the role of dissipation, we examine the interference pattern in a double-slit experiment while considering both effects. To do so, we establish time scales for decoherence and dissipation and acknowledge the possibility of these effects occurring in close proximity. By comparing the relative intensity and fringe visibility between a purely decoherent model and a model that incorporates both decoherence and dissipation, we observe that when the time scales of decoherence and dissipation are similar, there exists a propagation time interval where dissipation contributes to a faster degradation of quantum features compared to the sole influence of decoherence. Hence, it is crucial to consider both decoherence and dissipation effects, especially when their time scales are closely aligned, to gain a comprehensive understanding of quantum behavior.
We discuss Young's double-slit experiment using a partially coherent light source consisting of a helium-neon laser incident on a rotating piece of white paper. Such an experiment is appropriate for undergraduate students as an independent project or as part of an advanced lab course. As is well known, the resulting interference pattern is observed to disappear and return, depending on the angular size of the source. Interestingly, while the standard theoretical prediction for the light intensity agrees quite well with experimental data when the fringe visibility is high, the prediction is noticeably off when the visibility is low. A first-principles calculation of the light intensity is performed and shown to agree extremely well with the experimental results for all visibilities.