Descriptions of quadratic plus linear operators which preserve pure states of the quantum system

As we knew, a mathematical formalism of a quantum mechanics says that any quantum system is identified with some finite- or infinite-dimensional Hilbert space; pure states correspond to vectors of norm 1; observables are self-adjoint operators on the space of states. Thus the set of all pure stat...

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Bibliographic Details
Main Author: Saburov, Mansoor
Format: Proceeding Paper
Language:English
Published: 2013
Subjects:
Online Access:http://irep.iium.edu.my/33661/1/Paper_for_IREP.pdf
Description
Summary:As we knew, a mathematical formalism of a quantum mechanics says that any quantum system is identified with some finite- or infinite-dimensional Hilbert space; pure states correspond to vectors of norm 1; observables are self-adjoint operators on the space of states. Thus the set of all pure states corresponds to the unit sphere in the Hilbert space [1-2]. It is of interest to describe all linear or nonlinear operators which preserve the pure states of the system. In the linear case, it is nothing more than isometries of Hilbert spaces [1]. In the nonlinear case, this problem was open. In this paper we shall describe all quadratic plus linear operators which preserve pure states of the quantum system.!