Quantum Mechanics with Real Numbers: Entanglement, Superselection Rules and Gauges

We show how imaginary numbers in quantum physics can be eliminated by enlarging the Hilbert space followed by an imposition of—what effectively amounts to—a superselection rule. We illustrate this procedure with a qubit and apply it to the Mach–Zehnder interferometer. The procedure is somewhat remi...

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Bibliographic Details
Main Author: Vlatko Vedral
Format: Article
Language:English
Published: Quanta 2023-09-01
Series:Quanta
Online Access:https://dankogeorgiev.com/ojs/index.php/quanta/article/view/79
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Summary:We show how imaginary numbers in quantum physics can be eliminated by enlarging the Hilbert space followed by an imposition of—what effectively amounts to—a superselection rule. We illustrate this procedure with a qubit and apply it to the Mach–Zehnder interferometer. The procedure is somewhat reminiscent of the constrained quantization of the electromagnetic field, where, in order to manifestly comply with relativity, one enlarges the Hilbert Space by quantizing the longitudinal and scalar modes, only to subsequently introduce a constraint to make sure that they are actually not directly observable. Quanta 2023; 12: 164–170.
ISSN:1314-7374