by “Is nature an impostor?” On Tuesday, the Nobel Committee raised that question about what may be nature’s tiniest transgression: quantum mechanics.
Quantum mechanics is an area of physics that deals with all things subatomic. This field throws a wrench into pre-existing classical physics, which gave us the Standard Model that explains three of the four forces of the universe and defines all known subatomic particles. Quantum mechanics tries to predict where a particle will be at any given moment. Simple things.
There is a particularly difficult aspect of quantum mechanics known as entanglement. This phenomenon occurs when two particles, even if they are far from each other, act together. Effects on one particle will also affect its pair. Even though they are separate, they work as a single unit. Einstein described this behavior as “spooky energy at a distance.”
This year, Alain Aspect, John Clauser and Anton Zeilinger share the Nobel Prize in Physics for their respective contributions to quantum mechanics, showing not only its theoretical capabilities but also that photons in entangled states are all around us.
How it all started – Irish physicist John Stewart Bell published a paper in 1964 that developed a mathematical inequality known as Bell’s inequality. According to this principle, if there are hidden variables within the confounded pair, then the correlation between the results of a large number of measurements will always remain within certain limits.
Quantum mechanics, however, says that some kind of experiment will violate Bell’s inequality. This violation implies a stronger correlation than thought possible between two particles.
How this changed science as we know it – The American John Clauser created a practical experiment from Bell’s theory. He is the one who found the experiment that violated Bell’s inequality while supporting quantum mechanics, meaning that a theory using hidden variables cannot replace quantum mechanics.
Alain Aspect of France further built on this finding, closing a gap in Clauser’s finding. Modified the measurement settings of the experiment after ejecting a entangled pair from its source. The existing setting then could not affect the resulting measurements.
Austrian Anton Zeilinger played with these entangled quantum states. His research illustrated a principle called quantum teleportation, in which a particle can move quantum states across a distance.
Why these discoveries are important — One goal of quantum engineering, says the Nobel Committee, is to build a quantum network. They describe this network as a series of nodes that use quantum entanglement to communicate. This network has applications in cryptography and quantum computing, which can synthesize astronomical amounts of information.
Understanding entanglement is key, as it is what binds this network together. However, entanglement is fragile and breaks down in optical fibers intended to transmit it.
Recipient Anton Zeilinger said on a call when the award was publicly announced that the next generation will be the one to answer the remaining questions. “This award is an encouragement to young people,” he said. He also recognized the more than 100 students he had worked with to get this far. While physicists have made strides in this area, there is still a long way to go.
