Discriminating orthogonal single-photon images

We can encode an image from an orthogonal basis set onto a single photon from a downconverted pair via the use of an amplitude mask. We can then discriminate the image imprinted on the photon from other images in the set using holographic-matched filtering techniques. We demonstrate this procedure experimentally for an image space of two objects, and we discuss the possibility of applying this method to a much larger image space. This process could have important implications for the manipulation of images at the quantum level.

Figure 1

Concept of the experiment. A multiple-exposure hologram (shown for two exposures) is formed as shown in parts (a) and (b) of the figure. (c) An image is impressed onto a single photon and the form of the image is determined by diffraction from the hologram.

Figure 2

(Color online) Single-photon image-discrimination laboratory setup. (a) Biplex holograms are exposed using a HeNe laser and an electronically controlled shutter. For each exposure a rotation stage selects one of the two reference beams, and a translation stage switches between the two stencils A and B. (b) During the image-discrimination phase of the experiment, heralded single photons are sent through either stencil A or B and are detected at either detector A or B. $\text{TCSPC}=\text{time-correlated}$ single-photon counter.

Figure 3

(Color online) (a) and (b) Hologram readout for a plane-wave read beam. (c) and (d) Hologram readout with an image-carrying read beam.

Figure 4

(Color online) Graphical display of image-discrimination results. Total number of raw coincidences $\left(C\right)$, accidental coincidences $\left(A\right)$, and $C/A$ ratio for each object-detector combination.