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Tuesday, June 7, 2011

Textbook denies wave-duality

Apparently some physicists reject one of the fundamental premises of quantum mechanics, such as this:
At least one physicist considers the “wave-duality” a misnomer, as L. Ballentine, Quantum Mechanics, A Modern Development, p. 4, explains:

When first discovered, particle diffraction was a source of great puzzlement. Are "particles" really "waves?" In the early experiments, the diffraction patterns were detected holistically by means of a photographic plate, which could not detect individual particles. As a result, the notion grew that particle and wave properties were mutually incompatible, or complementary, in the sense that different measurement apparatuses would be required to observe them. That idea, however, was only an unfortunate generalization from a technological limitation. Today it is possible to detect the arrival of individual electrons, and to see the diffraction pattern emerge as a statistical pattern made up of many small spots (Tonomura et al., 1989). Evidently, quantum particles are indeed particles, but whose behaviour is very different from classical physics would have us to expect.
Electrons have been observed for a century, including the Millikan oil drop experiment, electron mass-to-charge ratio, and cloud chamber. The double-slit experiment was first done with light in 1801.

Here is a 2003 announcement:
Physicists at Rice University have completed the first real-time measurement of individual electrons, creating an experimental method that for the first time allows scientists to probe the dynamic interactions between the smallest atomic particles.

The research, which appears in the May 22 issue of the journal Nature, is important for researchers developing quantum computers, a revolutionary type of computer that is orders of magnitude more powerful than any computer ever built.

To date, computers have used the binary bit — represented by either a one or zero — as their fundamental unit of information. In a quantum computer, the fundamental unit is a quantum bit, or qubit. Because qubits can have more than two states, calculations that would take a supercomputer years to finish will take a quantum computer mere seconds.

Due to the complexities of quantum dynamics, electrons can serve as qubits. They can exist in "up" and "down" states -- single points that are analogous to the ones and zeroes in classical computers -- or in "superposition" states, which are not single points but patterns of probability that exist in several places at once.
All these high-tech experiments haven't given us any better understanding of electrons than Bohr had, and haven't brought us any closer to qubits. Bohr's complementarity arguments are just as valid today. Saying that particles have been detected makes no more sense than saying that waves have been detected.

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