Figure 4: Quantum trajectories.

(a,b) Quantum trajectories of spontaneous decay calculated by the stochastic master equation, initialized at −z (a) and +x (b). Several trajectories are depicted in grey, and a few individual trajectories are highlighted in black. (c,d) Individual trajectories that originate from −z (c) and +x (d) are shown as dashed lines and the tomographic reconstructions (Methods section) based on projective measurements are shown as solid lines. (e) For trajectories that are initialized along +x some are excited (attaining values below a threshold z′). (f) Fraction of the trajectories that are excited below the threshold z′ versus time.