Mermin's pentagram as an ovoid of PG(3, 2)

M. Saniga, P. Lévay

Research output: Contribution to journalArticle

12 Citations (Scopus)


Mermin's pentagram, a specific set of ten three-qubit observables arranged in quadruples of pairwise commuting ones into five edges of a pentagram and used to provide a very simple proof of the Kochen-Specker theorem, is shown to be isomorphic to an ovoid (elliptic quadric) of the three-dimensional projective space of order two, PG(3, 2). This demonstration employs properties of the real three-qubit Pauli group embodied in the geometry of the symplectic polar space W(5, 2) and rests on the facts that: 1) the four observables/operators on any of the five edges of the pentagram can be viewed as points of an affine plane of order two, 2) all the ten observables lie on a hyperbolic quadric of the five-dimensional projective space of order two, PG(5, 2), and 3) that the points of this quadric are in a well-known bijective correspondence with the lines of PG(3, 2).

Original languageEnglish
Article number50006
Issue number5
Publication statusPublished - Mar 1 2012

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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