Flexi Says: Quantum entanglement occurs when two subatomic particles (or systems made up of multiple particles) share quantum characteristics such as spin and momentum, and when the characteristics of one particle change, the same change instantly occurs in the other particle regardless of how far apart the particles are in space. If you think that sounds odd, so did Einstein who referred to this phenomenon as "spooky action at a distance." However, quantum entanglement has been repeatedly observed, tested, and confirmed by a large number of studies. Engineers are even learning to use this phenomenon to build quantum computers!