Antiunitary operator

In mathematics, an antiunitary transformation, is a bijective antilinear map between two complex Hilbert spaces such that for all and in , where the horizontal bar represents the complex conjugate. If additionally one has then is called an antiunitary operator. Antiunitary operators are important in quantum theory because they are used to represent certain symmetries, such as time reversal. Their fundamental importance in quantum physics is further demonstrated by Wigner's theorem. rdf:langString