Mirjana Božić

Should particle trajectories comply with the transverse momentum distribution

Abstract.The momentum distributions associated with both the wave function of a particle behind a grating and the corresponding Bohmian trajectories are investigated and compared. Near the grating, it is observed that the former does not depend on the distance from the grating, while the latter changes with this distance. However, as one moves further apart from the grating, in the far field, both distributions become identical.

Full quantum mechanical analysis of atomic three-grating Mach-Zehnder interferometry

Abstract Atomic three-grating Mach–Zehnder interferometry constitutes an important tool to probe fundamental aspects of the quantum theory. There is, however, a remarkable gap in the literature between the oversimplified models and robust numerical simulations considered to describe the corresponding experiments. Consequently, the former usually lead to paradoxical scenarios, such as the wave–particle dual behavior of atoms, while the latter make difficult the data analysis in simple terms. Here these issues are tackled by means of a simple grating working model consisting of evenly-spaced Gaussian slits. As is shown, this model suffices to explore and explain such experiments both analytically and numerically, giving a good account of the full atomic journey inside the interferometer, and hence contributing to make less mystic the physics involved. More specifically, it provides a clear and unambiguous picture of the wavefront splitting that takes place inside the interferometer, illustrating how the momentum along each emerging diffraction order is well defined even though the wave function itself still displays a rather complex shape. To this end, the local transverse momentum is also introduced in this context as a reliable analytical tool. The splitting, apart from being a key issue to understand atomic Mach–Zehnder interferometry, also demonstrates at a fundamental level how wave and particle aspects are always present in the experiment, without incurring in any contradiction or interpretive paradox. On the other hand, at a practical level, the generality and versatility of the model and methodology presented, makes them suitable to attack analogous problems in a simple manner after a convenient tuning.

Coherence loss and revivals in atomic interferometry: a quantum-recoil analysis

The coherence effects induced by external photons coupled to matter waves inside a Mach–Zehnder three-grating interferometer are analyzed. Alternatively to atom–photon entanglement scenarios, the model considered here only relies on the atomic wavefunction and the momentum shift induced in it by the photon scattering events. A functional dependence is thus found between the observables, namely the fringe visibility and the phase shift, and the transversal momentum transfer distribution. Good quantitative agreement is found when comparing the results obtained from our model with the experimental data.

Quantum Interference, Quantum Theory of Measurement, and (In)completeness of Quantum Mechanics

The new techniques and ideas in quantum interferometry with neutrons, photons, atoms, electrons, and Bose condensates that fluorished in the last two decades have influenced in a decisive way the thinking and the research in the foundations and interpretation of quantum mechanics. The controversies existing among different schools on the reality of matter waves of quantum theory, the postulates of quantum measurement theory, and the (in)completeness of quantum mechanics have to be approached now in a new way. Our argumentation follows the spirit of the Paris school.

Compatible statistical interpretation of a wave packet

A compatible statistical interpretation of a wave packet is proposed. De Broglian probabilities which unite wave and particle features of quantons are evaluated for free wave packets and Jor a superposition of wave packets. The obtained expressions provide a very plausible and physically appealing explanation of coherence in apparently incoherent beams and of the characteristic modulation of the momentum distribution, found recently in neutron interferometry combined with spectral filtering. Certain conclusions about dualism and objectivity in quantum domain are also derived.

Comparison of Wigner’s Function and de Broglian Probability Density for a Wave Packet and the Wave Packets Superposition

Compatible statistical interpretation (CSI) of Quantum mechanics (QM), proposed recently [1], is a specific synthesis of Born’s statistical interpretation (SI) of QM and of L. de Broglie’s wave mechanics [2]. To the set of Born’s probabilities of SI, CSI adds a kind of joint probability density of quantities associated with non-commuting operators. This probability density, named De Broglian, incorporates into QM the standpoint of L. de Broglie [2], Vigier, Selleri, and Bohm and Hiley [3] that wave and particle properties are compatible (contemporary).

QUANTUM BEATS DESCRIBED BY DE BROGLIAN PROBABILITIES

Compatible statistical interpretation is used to give objective interpretation of quantum beats in atomic fluorescence.

Trends in the Presence and Roles of Women Physicists in Serbia

In general, the portion of women in physics has been increasing in recent years in Serbia, as well as their presence in research and academic institutions. The percentage of women who earned BSc degrees in physics is greater than men. In this respect the situation in Serbia is different from most other countries. But more men than women earned MSc and PhD degrees.

Theory Of Interference Of Large Molecules

In the experiments with large molecules, the diameter of particles has approached the width of the slits. Therefore, a theoretical description of these cases should include a finite particle size. We are developing a theory of quantum interference which takes into account the trajectories and the size of particles. The theory uses a distribution of transverse momenta of particles to describe emergence of an interference pattern during accumulation of single particle arrivals to the screen. In this way we are accomplishing the task which Barut assigned to theoretical physicists by writing: “It now becomes a task of theoretical physics to build models and theories of single events, and a task of experimental physics to record more of single events”.