Component explanations

Polarized Beam Splitter (PBS)

Let’s start with our first and most used component, the polarized beam splitter. A PBS is an optical component meant to separate between the horizontal and vertical polarization. This simply means that if a photon is vertically polarized (in relation to the component’s orientation) it will pass through it normally but, if it’s horizontally polarized, it will get reflected 90° as shown by the graphic below.

PBS

Polarization Rotator/Pauli-X

A polarization rotator is a pretty simple optical component. All it does, is rotate the polarization axis by an angle θ. So if θ = 90° a vertically polarized photon becomes horizontally. This means that if the angle θ = 90° the rotator works exactly like a Pauli-X also known as a bit flip!

Polarization rotator by wikipedia

Photomultiplier Tube

Photomultiplier tubes work as very sensitive light detectors, that are able to detect individual photons. To do this they use a phenomenon known as photoelectric effect some electrons get ejected.

Photomultiplier tubes