Researchers set ‘ultrabroadband’ record with entangled photons

Quantum entanglement—or what Albert Einstein once referred to as “spooky action at a distance”— occurs when two quantum particles are connected to each other, even when millions of miles apart. Any observation of one particle affects the other as if they were communicating with each other. When this entanglement involves photons, interesting possibilities emerge, including entangling the photons’ frequencies, the bandwidth of which can be controlled.