Nonuniqueness of the C operator in PT-symmetric quantum mechanics

The C operator in PT-symmetric quantum mechanics satisfies a system of three simultaneous algebraic operator equations, C^2=1, [C,PT]=0, and [C,H]=0. These equations are difficult to solve exactly, so perturbative methods have been used in the past to calculate C. The usual approach has been to express the Hamiltonian as $H=H_0+\epsilon... Show more