ContentThis course is a survey of wave physics.We'll start with material such as waves moving along a string and waves rippling across a pond before progressing to wave concepts which might challenge your view of reality. If you crack a whip, it sends a density ripple through a medium of air.We sense this as sound. Jostling an electron causes it to emit traveling electric and magnetic fields.We sense this as light.
ContentThis course is a survey of wave physics.We'll start with material such as waves moving along a string and waves rippling across a pond before progressing to wave concepts which might challenge your view of reality. If you crack a whip, it sends a density ripple through a medium of air.We sense this as sound. Jostling an electron causes it to emit traveling electric and magnetic fields.We sense this as light.
Wave motion exists everywhere. When a bird sings in the forest, sound waves propagate away from the bird’s throat in all directions, striking the ear membranes of the other animals nearby. A leaf falling from a tree on the surface of a pond produces ripples that spread outward through the surface of the serene water. Light reaching the surface of the earth from the sun propagates through empty space as an electromagnetic wave. And as we learned in Chapter 7, even ordinary matter exhibits wave behavior.
At least three authors have proposed the concept of light as a traveling series of ‘matter waves.’ Such a concept does not require an ‘aether’ medium as does the more prevalent concept of light, if behaving as a wave, doing so analogous to other types of ‘disturbance waves,” such as sound or water. One author’s concept is examined mathematically for plausibility and, when found to be so, extended qualitatively to incorporate that of the other authors’ to at least what is hoped may be viewed as a reasonable extent.
The puzzles of quantum mechanics are: 1. What is the medium for the photon and for the electron wave? i.e. what is waving? 2. How can a particle have an interference pattern 3. Observer effect. 4. Entanglement. In Quantum Erasure and Double-Slit experiments, how does the emitter know to direct the photon two both slits or only to one slit? And how does the detector know where to detect the photons to form an interference pattern and not a bell-shaped (Gaussian) pattern or vice versa? This paper proposes that the hint in the mystery of light waves without a medium (ether) is contained in the Planck’s relation itself: E = hf. It is shown that Planck’s relation itself hints on the mystery of light waves without medium, and is a consequence or manifestation of non-existence of a medium for light propagation. The subtle law of nature that has eluded physicists so far is that the photon energy density ( amplitude of electric and magnetic fields) at a given point in the spatial dimensions of the photon is directly related to the rate of change of the electric and magnetic fields at that point. The higher the frequency of the photon, the higher the rate of change of the fields at every point for that photon, compared to a photon of lower frequency. The higher the rate of change of the fields at a given point, the higher the amplitude of oscillation of the electric and magnetic fields at that point. It follows that the higher the frequency of the photon and the higher the amplitude of the electric and magnetic fields, which results in high intensity of vibration of the photon, the more localized it will be. A high frequency photon will spread less in space than a lower frequency photon of equal envelope amplitude because, if the high frequency photon spreads out, there would be high rates of change over a wider region of space, and the total energy would be greater than the finite photon energy. The photon energy will always be concentrated at regions of high rate of change of electric and magnetic fields. This theory explains how electric and magnetic fields can be their own ‘medium’ , 'dragging' of the electromagnetic energy by the wave, hence eliminating the need for any medium. Since the electromagnetic wave (the photon) is a traveling disturbance of electric and magnetic fields, the rate of change of the fields at a point in space will create the intensity (amplitude) of the fields at that point. Likewise, the electron wave is a travelling disturbance of the electron mass density wave on the electron ‘sea’. The higher the frequency of mass density variation of the electron at a given point of space, the higher the mass density of the electron at that point. This will make the electron ( the electron ‘sea’) its own medium of propagation. i.e. the electron ‘sea’ is the medium of propagation for the electron wave. This means that the electron wave 'drags' the electron with itself. The other theory proposed in this paper is the predetermination of interference fringes in double-slit experiments and predetermination of which slit the photon takes in which-way or quantum erasure experiments. We propose a fundamental law of nature that an electron, an atom or any source of electromagnetic waves will always emit a weak, continuous electromagnetic energy even when not excited, which implies that electrons and atoms are always in continuous, fundamental, weak vibrations (accelerations). Therefore, in double-slit experiments and in quantum erasure or which-way experiments, the atom (electron) of the light source is always emitting weak, continuous electromagnetic waves, even before the atom is excited. Therefore, even before the atom/the electron of the light source starts emitting a photon, a weak electromagnetic (light) wave exists as an entity, extending all the way from the light source (the atom) to the slits and to the detecting screen. This ‘precursor’ wave serves as the 'highway' for the propagation of the main photon energy packet, both of which are coherent and exist as an entity. When the atom is excited, it will just emit a photon that is coherent with the weak wave it had already been emitting continuously. Therefore, even before the atom is excited, a weak wave interference pattern already exists on the screen. The photon emitted after excitation simply follows the path already created by the weak ‘precursor’ wave and will land on the screen according to the predetermined interference pattern, collapsing to the point of detection at the instant of detection. The path to be taken by the photon is predetermined in which-way or quantum erasure experiments. The same theory explains quantum entanglement: the polarization of two entangled photons is predetermined even before the excitation of the atoms emitting the photons.
In a period when a limited domain of physical phenomena is exciting wide fervent interest and commanding intensive study, and continues for years to monopolize the attention of many brilliant theorists, sometimes it is the fortune of an ingenious mind to express or interpret or picture the already-discovered laws in a new way which makes so greatly favourable an impression, that in a moment it sweeps its rivals from the field. The new theory may not lead to more or better agreements with experience than did its predecessors; it need not make predictions which they were incapable of making; its mathematical processes may be identical with theirs, the old symbols reappearing with new names in the old equations. Contrariwise it may be born well endowed with these advantages which normally decide the contest between old theories and new, yet owe its victory not to them at all. It triumphs because it seems natural or sensible or reasonable or elegant or beautiful-words said of a theory which fulfils some deep-seated demand or evades some deep-rooted prejudice in the minds of its judges. Later its vogue may pass, not through the disclosure of any intrinsic defect, but because the physicists of the rising generation do not share the prejudices and the predilections of those who first applauded it. The kinetic theory of gases was welcomed by a generation which wished to believe in atoms; the electromagnetic theory by people prejudiced against the notion of action at a distance; the quantum-theory has always had to do battle against those who yearn for continuity in their images of Nature, and the theory to which these pages are devoted has captivated the world of physics in a few brief months because it seems to promise a fulfilment of that long-baffled and insuppressible desire.
Quantum Mechanics: An Introduction for Device Physicists and Electrical Engineers, Fourth Edition provides a complete course in quantum mechanics for students of semiconductor device physics and electrical engineering. It provides the necessary background to quantum theory for those starting work on micro- and nanoelectronic structures and is particularly useful for those beginning work with modern semiconductors devices, lasers and qubits. This book was developed from a course the author has taught for many years with a style and order of presentation of material specifically designed for this audience. It introduces the main concepts of quantum mechanics which are important in everyday solid-state physics and electronics. Each topic includes examples which have been carefully chosen to draw upon relevant experimental research. It also includes problems with solutions to test understanding of theory. Fully updated throughout, the fourth edition contains the latest developments, experiments, and device concepts. It contains completely new material on quantum computing and information processing, including qubit implementations and quantum sensing. Key features: Fully updated throughout with the latest research from the field Presents a different view of quantum mechanics from an engineering perspective Takes a modern view of the understanding of quantum mechanics as it affects real world technologies, including nanotechnology and quantum information processing