Wigner's theorem on Grassmann spaces

Geher, G. P. (2017) Wigner's theorem on Grassmann spaces. Journal of Functional Analysis, 273 (9). pp. 2994-3001. ISSN 0022-1236 doi: 10.1016/j.jfa.2017.06.011

Abstract/Summary

Wigner's celebrated theorem, which is particularly important in the mathematical foundations of quantum mechanics, states that every bijective transformation on the set of all rank-one projections of a complex Hilbert space which preserves the transition probability is induced by a unitary or an antiunitary operator. This vital theorem has been generalised in various ways by several scientists. In 2001, Molnár provided a natural generalisation, namely, he provided a characterisation of (not necessarily bijective) maps which act on the Grassmann space of all rank-n projections and leave the system of Jordan principal angles invariant (see [17] and [20]). In this paper we give a very natural joint generalisation of Wigner's and Molnár's theorems, namely, we prove a characterisation of all (not necessarily bijective) transformations on the Grassmann space which fix the quantity TrPQ (i.e. the sum of the squares of cosines of principal angles) for every pair of rank-n projections P and Q.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/70779
Identification Number/DOI	10.1016/j.jfa.2017.06.011
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Mathematics and Statistics
Publisher	Elsevier
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