Fig. 1. Schematic diagram of the principle and experimental setup for quantum 3D OAM holography. (a) Principle of quantum 3D OAM holography. A 3D OAM multiplexing hologram with three OAM channels (colors represent individual OAM values) and two imaging planes are placed at the signal arm, and the switchable holography display is controlled by the post-selection of the OAM states in the idler arm. (b) Schematic of the experimental setup. A wide collimated light at 405 nm pumps the PPKTP crystal to generate OAM-entangled photon pairs at 810 nm. After spectral filtering and expansion, the signal photons and the idler photons are separated through their polarization. A forked grating is loaded on SLM-A to project the idler photon with corresponding OAM states into a single-mode fiber connected to an SPAD, realizing the post-selection of signal-photon states. A half-wave plate (HWP) in the signal arm changes the polarization of the signal photons to match the working polarization of SLM-B. After a 35 m delay line, the signal photons illuminate the OAM multiplexing hologram loaded on SLM-B and then pass through lens F_L to generate a far-field diffraction pattern at the ICMOS camera. The ICMOS camera is externally triggered by idler photon events. PBS, polarizing beam splitter; HWP, half-wave plate; RAP, right-angle prism; FC, fiber coupler.

Fig. 2. Visualized demonstration of quantum OAM preserved holography and OAM selective holography. (a) Sketch map of quantum OAM preserved holography and OAM selective holography. The difference between them is that OAM encoding is applied to the OAM selective hologram while it is absent in the OAM preserved hologram. (b) Results of quantum OAM preserved holography heralded by the idler photon OAM state of l_i = |1⟩ and l_i=12(|2⟩+|−2⟩). The enlarged area in the map is an astigmatic transformation pattern that can verify that these pixels do inherit the OAM state of l_s = −1 and l_s=12(|−2⟩+|2⟩). (c) Experimental results of OAM selective holography.

Fig. 3. Quantum OAM multiplexing holography. (a) The process for implementation of OAM multiplexing holography. Coincidental imaging between the OAM multiplexing hologram in the signal arm and fork grating in the idler arm directly gives the original holographic reconstruction result on the ICMOS camera with the post-selection of a specific OAM state of l_i = −2. Only the image (the letter “C”) with the corresponding encoded OAM value (l_sn = −2) will possess pixels with the basic Gaussian mode. (b) Holographic reconstruction results heralded by corresponding idler photon states when an aperture array is applied.

Fig. 4. The performance of quantum OAM-multiplexing 3D holography. (a) Quantum holography for three OAM channels and two imaging planes with a distance of 300 mm. (b) The dependence of the SNR with a distance of the two imaging planes.