Category: Entanglement

Each photon in an entangled-photon pair is just a photon, and like any other photon, it can be detected using the type of methods that we used (Figure 33) to detect individual photons. However, recall that the quantum efficiency of the PMT probe that we built (Figure 30) was quite low, even at high photon…

Before we go any further, we want to warn you that many of the experiments described are out of the budget of many enthusiasts. This is because applications involving quantum entanglement are in the early stages of development, so the specialized crystals and detectors are not yet mass-produced. However, we feel that it is worthwhile…

The debate between Einstein and Bohr continued for decades regarding what “reality” meant in the context of quantum mechanics. Einstein and his followers insisted that an objective reality exists whether it is observed or not. Their most powerful argument was explained in the EPR paper, in which Einstein and his colleagues proposed that “elements of…

The quantum eraser experiment, which seems to indicate that the photon “knows” when we—the observers*—are watching. Indeed, the photon behaves very differently when we—the observers—can say (at least in principle) which path it has traveled. The thought that an objective reality does not exist independently of an observer troubled Einstein very much. In opposition to…