Fig. 4: Coherence below and above condensation threshold.

a Real-space interferograms of the emitted signal below (top panels, ∼0.2 P_th, exposure time 10 s) and above (bottom panels, ∼2.4 P_th, exposure time 1.5 s) condensation threshold. While for Δt = 0 ps interference fringes are observed in both cases, below threshold the fringes have already disappeared after ∼0.1 ps, while they are still visible even after ∼2.8 ps above threshold. b Extracted fringe visibility of the interfered condensate signal at ∼2.4 P_th excitation fluence for different time delays Δt. The fringe visibility at each time delay Δt was calculated from the Fourier transform of the images, by dividing the signal at the fringes’ spatial period by the total signal of the whole Fourier transformed image. Finally, this fringe visibility is calibrated by comparison with the visibility at zero time delay obtained directly from the fringe minima/maxima in the real space image. Fitting the experimental data with a Gaussian function (red dashed line) shows an extended temporal coherence with 5.2 ps FWHM autocorrelation decay.