Albert Einstein would be rolling in his grave today if he were to find that there is indeed an unusually spooky connection between particles.

Earlier in the last century, Einstein and other fellow renowned physicists concluded that quantum entanglement — the more scientific description of that "spooky action at a distance" between particles — was either impossible or that there was some hidden variable affecting the states of both particles.

In everyday speak, quantum entanglement simply means that when something happens to a particle, something happens to the other particle it is inextricably linked to, no matter how far apart the two particles are from each other. In this synchronous relationship between a pair of particles, the change in one is instantaneously relayed to the other at speeds faster than that of light.

Einstein famously refused to believe that this phenomenon was a real thing as it violated the intricate workings of his special theory of relativity, which implies that nothing could travel faster than the speed of light.

It took some time for quantum entanglement to be accepted as a fact of nature. The phenomenon has proven to be extremely elusive, and linking particles together does appear to be impossible, but it can be done. In one experiment, two particles were separated by a distance of 89 miles and still the "spooky action" occurred. After many other experiments, the loopholes surrounding the validity of the phenomenon were deemed closed.

Most recently, an even more successful set of experiments were concluded in which quantum entanglement was achieved at room temperature.

About the state of quantum-entangled particles at room temperatures, David Aschalom, a senior scientist at the Argonne National Laboratory, notes that "they are coherent, long-lived and controllable with photonics and electronics. Given these quantum 'pieces,' creating entangled quantum states seemed like an attainable goal."

What could quantum entanglement be used for, exactly? Quantum encryption, a perfectly secure method of encryption, is one such application. Aside from providing more secure communication channels, long-distance entangled particle states could also better synchronize GPS systems around the world. Moreover, in the field of biomedicine, one exceptional innovation using quantum entanglement is in the biological sensing of a quantum device inside a living organism.

"We are excited about entanglement-enhanced magnetic resonance imaging probes, which could have important biomedical applications," says Abram Falk of IBM's Thomas J. Watson Research Center.

The verified existence of the "spooky connection" between particles may be the end of one chapter in the long history of physics, but it also marks the beginning of another chapter in an exciting new field.

Photo: Thierry Ehrmann | Flickr 

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