Factoid of the day

Photons ignore each other....

Scitechdaily writes:  but now researchers have developed a quantum gate that uses a Qubit

In order for photons to sense each other’s presence in the first place, let alone switch each other, they need mediators.
In the experiments being conducted by Stephan Ritter’s team of physicists, this mediating role is taken on by a single atom in a resonator.
The resonator consists of two mirrors 0.5 mm apart. The Garching-based researchers use a laser beam to trap the atom in the resonator.
 For their experiments, the scientists now need two photons each carrying one qubit.
A qubit is the quantum mechanical equivalent of the bit of a conventional computer. It can, however, not only encode the zero and the one, but assume all possible states in between as well.
The researchers write the states of the two qubits into the polarization of the two light particles, i.e. into the direction of oscillation of the electromagnetic waves.