The spectrum of the Hamiltonian with a PT-symmetric periodic optical potential
The spectrum of the Hamiltonian with a PT-symmetric periodic optical potential
We give a complete description, provided with a mathematical proof, of the shape of the spectrum of the Hill operator with a PT-symmetric periodic optical potential. We prove that the second critical point, after which the real parts of the first and second bands disappear, is a number between 0.8884370025 …