Kramers' theorem

proper noun

A theorem stating that, for every energy eigenstate of a time-reversal symmetric system with half-integer total spin, there is another eigenstate with the same energy related by time-reversal. In other words, the degeneracy of every energy level is an even number if it has half-integer spin.

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Meanings

proper noun
  1. quantum mechanicsA theorem stating that, for every energy eigenstate of a time-reversal symmetric system with half-integer total spin, there is another eigenstate with the same energy related by time-reversal. In other words, the degeneracy of every energy level is an even number if it has half-integer spin.

Origin

Named after Dutch physicist H. A. Kramers.

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Cite this entry
APA

Kramers' theorem. (n.d.). In WatkinsX Dictionary. Retrieved November 5, 2026, from https://dictionary.watkinsx.com/word/Kramers'%20theorem

MLA

“Kramers' theorem.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/Kramers'%20theorem. Accessed November 5, 2026.

Chicago

WatkinsX Dictionary, s.v. “Kramers' theorem,” accessed November 5, 2026, https://dictionary.watkinsx.com/word/Kramers'%20theorem.

Source: Kramers' theorem on Wiktionary, CC BY-SA 4.0.