arXiv subjects

Robert E. Wyatt

Publications and source records attributed to Robert E. Wyatt.

5 recordsLinked to original sources

arXiv2011

Comment on "Observing the Average Trajectories of Single Photons in a Two-Slit Interferometer"

Kocsis et al. (Science, Reports 3 June 2011, p. 1170) state that the experimentally deduced average photon trajectories are identical to the particle trajectories of Bohm's quantum mechanics. No supporting evidence, however, was provided. The photon trajectories presented in their report do not converge to high probability regions, a familiar and necessary behavior of Bohm trajectories. We reanalyze their data and calculations, conclude that the average photon trajectories do indeed agree with Bohm, and discuss possible interpretations of this result.

quant-ph↗

arXiv2010

Quantum interference within the complex quantum Hamilton-Jacobi formalism

Quantum interference is investigated within the complex quantum Hamilton-Jacobi formalism. As shown in a previous work [Phys. Rev. Lett. 102, 250401 (2009)], complex quantum trajectories display helical wrapping around stagnation tubes and hyperbolic deflection near vortical tubes, these structures being prominent features of quantum caves in space-time Argand plots. Here, we further analyze the divergence and vorticity of the quantum momentum function along streamlines near poles, showing the intricacy of the complex dynamics. Nevertheless, despite this behavior, we show that the appearance of the well-known interference features (on the real axis) can be easily understood in terms of the rotation of the nodal line in the complex plane. This offers a unified description of interference as well as an elegant and practical method to compute the lifetime for interference features, defined in terms of the average wrapping time, i.e., considering such features as a resonant process.

quant-ph↗

arXiv2007

Uniqueness of Bohmian Mechanics, and Solutions From Probability Conservation

We show that one-dimensional Bohmian mechanics is unique, in that, the Bohm trajectories are the only solutions that conserve total left (or right) probability. In Brandt et al., Phys. Lett. A, 249 (1998) 265--270, they define quantile motion--unique trajectories are solved by assuming that the total probability on each side of the particle is conserved. They argue that the quantile trajectories are identical to the Bohm trajectories. Their argument, however, fails to notice the gauge freedom in the definition of the quantum probability current. Our paper sidesteps this under-determinedness of the probability current. The one-dimensional probability conservation can be used for higher dimensional problems if the wave function is separable. Several examples are given using total left probability conservation, most notably, the two-slit experiment.

quant-ph↗

arXiv2003

Quantum Mechanics with Trajectories: Quantum Trajectories and Adaptive Grids

Although the foundations of the hydrodynamical formulation of quantum mechanics were laid over 50 years ago, it has only been within the past few years that viable computational implementations have been developed. One approach to solving the hydrodynamic equations uses quantum trajectories as the computational tool. The trajectory equations of motion are described and methods for implementation are discussed, including fitting of the fields to gaussian clusters.

quant-ph↗

arXiv2002

Decoherence demystified : The hydrodynamic viewpoint

The hydrodynamic formulation of quantum mechanics is used to elucidate the mechanism for decoherence, the suppression of interference effects in a system evolving from an initial coherent superposition. Analysis of time-dependent trajectory ensembles, flux maps, and elements of the stress tensor for two composite systems, in one of which the system is uncoupled to the environment, leads to the decoherence mechanism. For the uncoupled case, the quantum force acting on the fluid elements directs flux toward an attractor where the interference feature arises. For the coupled case, the classical force acting on each fluid element counters the quantum force and leads to gradual separation of the components of the initial superposition. Concomitantly, fluid stress is relieved when flux vectors diverge from a repellor in the mid-region between the separating wavepackets, thus suppressing formation of the interference feature.

quant-ph↗