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arXiv · 1707.05313

Hidden antiunitary symmetry behind "accidental" degeneracy and its protection of degeneracy

Jing-Min Hou·Wei Chen
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Abstract

In quantum mechanics, accidental degeneracy refers to energy degeneracy that occurs coincidentally, without any protection by symmetry. Here, we prove a theorem stating that any two-fold degeneracy (accidental or not) in a quantum system is protected by a novel hidden symmetry, which can be expressed by an antiunitary operator with its square being -1. In this sense, the so-called accidental degeneracy is not really accidental, and this actually implies a hidden antiunitary symmetry.

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Jing-Min Hou, Wei Chen. 2017-07-17. Hidden antiunitary symmetry behind "accidental" degeneracy and its protection of degeneracy. https://doi.org/10.1007/s11467-017-0712-8

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