Figure 6: Measurement fringes as a function of Charles’ phases.

For each panel only one phase is varied while the others are fixed. (a) The theoretical fidelity range (Δf≡maximum−minimum) for the black, red and green curves are Δf=0.5, 1 and 0, respectively; (b) the theoretical fidelity range values are Δf=0, 0 and 1, respectively; (c) theoretical fidelity range values are Δf=1, 0 and 0, respectively. Error bars represent s.d. and are calculated through Monte Carlo simulation assuming Poissonian statistics. The larger-than-predicted fidelity range of some of these curves arises from crosstalk in the polarization/spatial-mode measurements. The missing strip of data around 180° in the final figure was due to instability in the active feedback system used to stabilize our interferometer at angles near this value of φ_c.