Ovidio Universe: How Quantum Entanglement works

 In quantum physics, entangled particles remain connected so that actions
performed on one affect the other, even when separated by great
distances. The phenomenon so riled Albert Einstein he called it “spooky
action at a distance.” The rules of quantum physics state that an
unobserved photon exists in all possible states simultaneously but, when
observed or measured, exhibits only one state. Spin is depicted here as
an axis of rotation, but actual particles do not rotate. Entanglement
occurs when a pair of particles, such as photons, interact physically. A
laser beam fired through a certain type of crystal can cause individual
photons to be split into pairs of entangled photons. The photons can be
separated by a large distance, hundreds of miles or even more. When
observed, Photon A takes on an up-spin state. Entangled Photon B, though
now far away, takes up a state relative to that of Photon A (in this
case, a down-spin state). The transfer of state between Photon A and
Photon B takes place at a speed of at least 10,000 times the speed of
light, possibly even instantaneously, regardless of distance. A proposed
experiment would send one photon of the entangled pair to the orbiting
International Space Station, a distance of around 310 miles (500
kilometers). This would be the largest distance that has been
experimentally tested.