Squeezed States in Josephson Junctions
Francesco Antonino Raffa · AIP conference proceedings · 2004
We consider the superconductive regime of a Josephson junction with an external biasing circuit. After recalling that the eigenvalue equation of the junction Hamiltonian HJ is a special case of the Mathieu equation, we diagonalize HJ in a suitable Fock space and prove that this leads quite naturally from the use of the two‐boson algebra. We utilize then the normalized even and odd coherent states of the two‐boson algebra to investigate the squeezing properties inherent in the nonlinearity of the junction with respect to the Cooper pair number and phase operators, N̂ and ϑ̂. This task is accomplished by utilizing the relationship between N̂, ϑ̂ and the generators of the dynamical quantum algebra of the junction.