Fig. 1. The three-dimensional and two-dimensional APTs of the twisted light (ℓ=1) in the double-slit interference. (a) Three-dimensional structures and their projections at the z=10zR plane (500 initial points for each slit). (b) Two-dimensional structures in the xz plane for 60 trajectories.

Fig. 2. Schematic diagram of experimental setup. HWP, half-wave plate; PBS, polarization beam splitter; L, lens; PPKTP, periodically poled KTP; IF, interference filter; QWP, quarter wave plate; FPC, fiber polarization controller; PAD, photon avalanche detector.

Fig. 3. Examples of 100 triggered coincidence images of ℓ=+1 OAM photons by the ICCD camera and the summing pattern of 100 frame images. Every acquired frame has an exposure time of 100 ms and is photon sparse.

Fig. 4. Triggered images by the ICCD for different exposure times, for the ℓ=+1 OAM twisted photons. (a) The ℓ=+1 OAM twisted photons themselves and (b) in the double-slit interference. If the photons are detected one by one, the photons appear to be distributed quite randomly. As the total number of accumulated photons increases, the interference fringes appear.