Phase sensitive pumping and coherence of superposition states
M. C. de Oliveira, S. S. Mizrahi, M. H. Y. Moussa · Journal of Optics B Quantum and Semiclassical Optics · 2001
The continuous parametric pumping of a superconducting lossy QED cavity supporting a field prepared initially as a superposition of coherent states is discussed. In contrast to classical pumping, we verify that the phase sensitivity of the parametric pumping makes the asymptotic behaviour of the cavity field state strongly dependent on the phase θ of the coherent state |α⟩ = ||α|e iθ ⟩. Here we consider θ = π/4,-π/4 and we analyse the evolution of the purity of the superposition states with the help of the linear entropy and fidelity functions. We also analyse the decoherence process quantitatively through the Wigner function, for both states, verifying that the decay is slightly modified when compared to the free decoherence case: for θ = -π/4 the process is accelerated while for θ = π/4 it is delayed.