A new breakthrough in the strange business of “quantum entanglement” may make measuring eerily connected particles easier than ever, scientists say.
Under the mind-bending rules of quantum mechanics, two particles can become entangled so that they retain a connection even when separated over long distances. The properties between the two are correlated so that an action performed on one will affect the other.
To study entangled particles, physicists have to be able to detect them. In some experiments, researchers measure one of the entangled pair first, and its presence signals, or “heralds,” the presence of the second particle. Recently, a team of physicists at the Joint Quantum Institute in College Park, Md., achieved a new record in heralding efficiency, meaning they were able to detect more twin particle pairs than ever before. [How Quantum Entanglement Works (Infographic)]
In the experiment, the researchers used what’s called a pump laser to produce a beam of light that passes through a special type of crystal. Occasionally, the photons of light in the laser beam will split in two, essentially, after passing through the crystal, creating a new pair of correlated photons. These photons will hit a detector screen exactly 180 degrees apart, so if the researchers find one, they know to look directly across the circle pattern formed on the detector, to the point 180 degrees around, to find the other.