Quantum Mechanics and Quantum Information Science: The Nature of Ψ\Psi

An overview is given of the nature of the quantum mechanical wave function.Comment: 8 pages, no figure; typo correcte

A Continuous Transition Between Quantum and Classical Mechanics (I)

In spite of its popularity, it has not been possible to vindicate the conventional wisdom that classical mechanics is a limiting case of quantum mechanics. The purpose of the present paper is to offer an alternative formulation of classical mechanics which provides a continuous transition to quantum mechanics via environment-induced decoherence.Comment: Revised version, to appear in Found. of Phy

Continuous Transitions Between Quantum and Classical Electrodynamics

The Maxwell equations in the presence of sources are first derived without making use of the potentials and the Hamilton-Jacobi equation for classical electrodynamics is written down. The manifestly gauge invariant theory is then quantized to write down the Hamilton-Jacobi equation in quantum electrodynamics. Finally, an interpolating field theory is proposed that describes continuous transitions between quantum and classical electrodynamics. It is shown that energy flow lines are identical for quantum and classical fields in the case of the double-slit arrangement but differ in the case of vortex beams.Comment: 7 pages, no figures; section 1.1 edited and shortened to make it more transparen

The Quantum-like Face of Classical Mechanics

It is first shown that when the Schr\"{o}dinger equation for a wave function is written in the polar form, complete information about the system's {\em quantum-ness} is separated out in a single term $Q$, the so called `quantum potential'. An operator method for classical mechanics described by a `classical Schr\"{o}dinger equation' is then presented, and its similarities and differences with quantum mechanics are pointed out. It is shown how this operator method goes beyond standard classical mechanics in predicting coherent superpositions of classical states but no interference patterns, challenging deeply held notions of classical-ness, quantum-ness and macro realism. It is also shown that measurement of a quantum system with a classical measuring apparatus described by the operator method does not have the measurement problem that is unavoidable when the measuring apparatus is quantum mechanical. The type of decoherence that occurs in such a measurement is contrasted with the conventional decoherence mechanism. The method also provides a more convenient basis to delve deeper into the area of quantum-classical correspondence and information processing than exists at present.Comment: 9 pages, no figure

The Unfinished Search for Wave-Particle and Classical-Quantum Harmony

The main purpose of this paper is to review the progress that has taken place so far in the search for a single unifying principle that harmonizes (i) the wave and particle natures of matter and radiation, both at the quantum and the classical levels, on the one hand and (ii) the classical and quantum theories of matter and radiation on the other hand. The famous paradoxes of quantum theory, the mysterious nature of measurements in quantum theory and the principal no-go theorems for hidden variables are first briefly reviewed. The Koopman-von Neumann Hilbert space theory based on complex wave functions underlying particle trajectories in classical phase space, is an important step forward in that direction. It provides a clear and beautiful harmony of classical waves and particles. Sudarshan has given an alternative but equivalent formulation that shows that classical mechanics can be regarded as a quantum theory with essentially hidden non-commuting variables. An extension of KvNS theory to classical electrodynamics provides a sound Hilbert space foundation to it and satisfactorily accounts for entanglement and Bell-CHSH-like violations already observed in classical polarization optics. An important new insight that has been obtained through these developments is that entanglement and Bell-like inequality violations are neither unique signatures of quantumness nor of non-locality---they are rather signatures of non-separability. Finally, Sudarshan's proposed solution to the measurement problem using KvNS theory for the measuring apparatus is sketched to show to what extent wave and particles can be harmonized in quantum theory.Comment: 28 pages, 3 figures; Journal of Advanced Physics, special issue on "Tests of Foundations of Quantum Mechanics", 201

Nonquantum Cognition

The Hilbert space structure of classical field theory is proposed as a general theoretical framework to model human cognitive processes which do not often follow classical (Bayesian) probability principles. This leads to an extension of the circumplex model of affect and a Poincar\'{e} sphere representation. A specific toy field theoretic model of the brain as a coherent structure in the presence of noise is also proposed that agrees qualitatively with Pavlovian fear conditioning studies.Comment: 24 pages, 2 figure

Entangling successive single-photons from quantum dots

A method is proposed for generating and discriminating Bell states of high fidelity from consecutive single-photons generated in a semiconductor quantum dot. The use of a non-symmetric beam splitter is found to be essential and sufficient, and no nonlinear optical process such as SPDC is required at any stage. This should be of considerable importance for testing the foundations of quantum mechanics.Comment: 10 pages, 1 figur

Comments on Struyve and Baere's paper on experiments to distinguish Bohmian mechanics from quantum mechanics

It is shown in detail why the arguments put forward by Struyve and Baere (quant-ph/0108038) against my conclusions are incorrect

Comments on "On Bohm trajectories in two-particle interference devices" by L. Marchildon

Marchildon's arguments against my earlier work are refuted.Comment: 4 pages, revtex, no figure

A Cosmology Inspired Unified Theory of Gravity and Electromagnetism: Classical and Quantum Aspects

Milne cosmology has recently been shown to be in broad agreement with most cosmological data while being free of the problematic notions of standard cosmology such as the dark sector. In this paper a broken symmetric unified theory of gravity and electromagnetism is introduced which has a Milne metric under a certain geometric condition. Strikingly, particles (dyons) emerge as topological charges in this theory provided the torsion vector $\Gamma_i$ is curl-less.Comment: 10 pages, no figure