Figure 4: Quantum interference visibility as a function of the diffracting laser power.
The best distinction between quantum and classical behaviour is made by tracing the interference fringe visibility as a function of the laser power, which determines the phase imprinted by the second grating. Each of the two experimental runs per molecule is represented by full circles and the error bar provides the 68% confidence bound of the sinusoidal fit to the interference fringe. The thick solid line is the quantum fit in which the shaded region covers a variation of the mean molecular velocity by Δv=±2 m s−1. (a) The TPPF84 data are well reproduced by the quantum model (see text) and completely missed by the classical curve (thin line on the left). (b) The same holds for PFNS8. The following parameters were used for the models: TPPF84: v=95 m s−1±16%, α=200 Å3×4πɛ0 (fit), σopt=10−21 m−2, wx=34±3 μm and wy=500±50 μm. PFNS8: v=75 m s−1±10%, α=190 Å3×4πɛ0 (fit), σopt=10−21m−2, wx=27±3 μm and wy=620±50 μm.
