Exact solution for particle trajectories in modified quantum mechanics

Considering a simple quantum master equation for a free particle we prove that after a given period of relaxation the solutions can be interpreted exactly in terms of uniform localized wave packets whose centers imitate classical trajectories.     

Completeness of observables and particle trajectories in quantum mechanics

The complete set of observables (bilinear Hermitian forms) is determined for the Schrödinger equation and their connection with the curvature and torsion of the curves, where conservation laws are fulfilled, is established. It is shown that these curves for a free particle, in the general case, are spiral lines with the radius and step length defined by the observables at the initial point (both parameters are proportional to the de Broglie wavelength). A spiral line turns to a straight line under some conditions. The trajectory variations are considered in the problem with a potential step and a rectangular barrier. It is shown that spiral lines can be transformed into straight lines and vice versa. All observables, which are changed along the potential barrier, can be restored under some constraints on the potential. The Hermitian transformations at the potential step are connected with the Lorentz transformations. A qualitative explanation of the double-slit experiment for extremely low intensity of the particles' source in the absence of the interference conditions is suggested.     

Exact two-particle S-matrix of quantum sine-Gordon solitons

The exact and explicit formulas for the quantumS-matrix elements of the soliton-antisoliton scattering which satisfy unitarity and crossing conditions and have correct analytical properties are constructed. ThisS-matrix is in agreement with the massive Thirring model perturbation theory and with the semiclassical sine-Gordon results.     

Coherent quantum oscillation trajectories

We discuss coherent oscillations in the quantum potential view of quantum mechanics, giving examples for both a superposition of position states, and a superposition of momentum states.     

Quaternionic quantum mechanics is consistent with complex quantum mechanics

Quaternionic quantum mechanics is investigated in the light of the great success of complex quantum mechanics. It is shown that to reproduce the results of complex quantum mechanics, quaternionic quantum mechanics must contain complex quantum mechanics.     

Realism in quantum mechanics

We first present a realistic framework for quantum probability theory based on the path integral formalism of quantum mechanics and illustrate this framework by constructing a model that describes a quantum particle evolving in a discrete space-time lattice. We then present a finite model for describing the internal dynamics of elementary particles and show that this model gives the standard particle classification scheme and successfully predicts particle masses.     

Decoherence in quantum mechanics

We study decoherence in a simple quantum mechanical model using two approaches. Firstly, we follow the conventional approach to decoherence where one is interested in solving the reduced density matrix from the perturbative master equation. Secondly, we consider our novel correlator approach to decoherence where entropy is generated by neglecting observationally inaccessible correlators. We show that both methods can accurately predict decoherence time scales. However, the perturbative master equation generically suffers from instabilities which prevents us to reliably calculate the system’s total entropy increase. We also discuss the relevance of the results in our quantum mechanical model for interacting field theories.     

Causality in quantum mechanics

We show explicitly how the causal arrow of time that follows from quantum mechanics has already been inserted at a deeper level by the choice of normalisation conditions. This prohibits information being sent backwards in time but does not determine a time direction for state propagation.     

Supersymmetry in quantum mechanics

In the past ten years, the ideas of supersymmetry have been profitably applied to many nonrelativistic quantum mechanical problems. In particular, there is now a much deeper understanding of why certain potentials are analytically solvable. In this lecture I review the theoretical formulation of supersymmetric quantum mechanics and discuss many of its applications. I show that the well-known exactly solvable potentials can be understood in terms of a few basic ideas which include supersymmetric partner potentials and shape invariance. The connection between inverse scattering, isospectral potentials and supersymmetric quantum mechanics is discussed and multi-soliton solutions of the KdV equation are constructed. Further, it is pointed out that the connection between the solutions of the Dirac equation and the Schrödinger equation is exactly same as between the solutions of the MKdV and the KdV equations.     

The transitions among classical mechanics,quantum mechanics,and stochastic quantum mechanics

Various formalisms for recasting quantum mechanics in the framework of classical mechanics on phase space are reviewed and compared. Recent results in stochastic quantum mechanics are shown to avoid the difficulties encountered by the earlier approach of Wigner, as well as to avoid the well-known incompatibilities of relativity and ordinary quantum theory. Specific mappings among the various formalisms are given.     

Existence of trajectories for Bohmian mechanics

We discuss the problem of global existence and uniqueness of Bohmian mechanics, focusing on the role played by the quantum probability flux. The relation to the self-adjointness of the Hamiltonian is alluded to.     

Magnetic moment of a two-particle bound state in quantum electrodynamics

A quasipotential method for calculating relativistic and radiative corrections to the magnetic moment of a two-particle bound state is formulated for particles of arbitrary spin. It is shown that the expression for the g factors of bound particles involve O(α ²) terms depending on the particle spin. Numerical values are obtained for the g factors of the electron in the hydrogen atom and in deuterium.