How fast is quantum entanglement?

The emergence of quantum entanglement is one of the fastest processes in nature. Scientists show that using special tricks, this can be investigated on an attosecond scale. Scientists have managed to analyze ulrafast processes which up until now were considered to be ‘instantaneous’: When a laser pulse hits an atom with two electrons, one electron may be ripped out of the atom, while the other electron stays close to the nucleus. These two electrons can become entangled in such a way that the point in time, at which the electron was ejected from the atom, becomes uncertain and depends on the state of the other electron.