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What Is Quantum Entanglement? A Physicist Explains Einstein’s “Spooky Action at a Distance”

When two particles are entangled, the state of one is tied to the state of the other.

Quantum entanglement is a phenomenon in which the quantum states of two or more objects become correlated, meaning that the state of one object can affect the state of the other(s) even if the objects are separated by large distances. This occurs because, according to quantum theory, particles can exist in multiple states at the same time (a concept known as superposition) and can be inextricably linked, or “entangled,” even if they are physically separated.

Three researchers were awarded the 2022 Nobel Prize in Physics for their ground-breaking work in understanding quantum entanglement, one of nature’s most puzzling phenomena.

Quantum entanglement, in the simplest terms, means that aspects of one particle of an entangled pair depend on aspects of the other particle, no matter how far apart they are or what lies between them. These particles could be, for example, electrons or photons, and an aspect could be the state it is in, such as whether it is “spinning” in one direction or another.

The strange part of quantum entanglement is that when you measure something about one particle in an entangled pair, you immediately know something about the other particle, even if they are millions of light years apart. This odd connection between the two particles is instantaneous, seemingly breaking a fundamental law of the universe. This is why Albert Einstein famously called the phenomenon “spooky action at a distance.”

Having spent the better part of two decades conducting experiments rooted in quantum mechanics, I have come to accept its strangeness. Thanks to ever more precise and reliable instruments and the work of this year’s Nobel winners, Alain Aspect, John Clauser, and Anton Zeilinger, physicists now integrate quantum phenomena into their knowledge of the world with an exceptional degree of certainty.

However, even until the 1970s, researchers were still divided over whether quantum entanglement was a real phenomenon. And for good reasons – who would dare contradict the great Einstein, who himself doubted it? It took the development of new experimental technology and bold researchers to finally put this mystery to rest.

Source: SciTechDaily