Figure 3
Coincidence counts RBP(τ1, τ2) of the BP state according to Eq. (33): the left panels from (a) to (d) refer to the case of θ = 0 (no achromatic phase shift), formally equivalent to the configurations analyzed in refs18,19,20,21,22,23,24; the right panels from (e) to (h) instead refer to the case of θ = π/2 (a quarter-wave plate contributes the achromatic phase shift). Panels (a) and (e): contour plots of RBP(τ1, τ2); Panels (b) and (f) plots of the function RBP(τ1, τ1); Panels (c) and (g) plots of RBP(τ1, 0); Panels (d) and (h) finally report RBP(0, τ2). In all the figures the delays times have been rescaled by the inverse of the width ΔΩ− of the bi-photon spectrum, and the rates have been rescaled by the plateau value RBP(0, ∞) = 1/2. The mean frequency ω0 was set equal to 5ΔΩ− and ΔΩ+ = ΔΩ−/5. Notice that RBP(τ1, τ1) is strictly positive for θ = 0, while for θ = π/2 it reaches zero only for τ1 = τ2 = 0.
