Researchers have combined two of the quantum world’s funkiest properties to set a new record — inextricably linking, or entangling, five light particles possessing the weird feature of “superposition.”
Superposition is a condition in which a light particle, or photon, exists in both of two possible states at once. The new work, described by Israeli researchers in the May 14 Science, paves the way for physicists to better control particles that are both superposed and linked by quantum entanglement. Potential applications include better microscopes or other instruments that involve light, or even future quantum measurement devices.
“It is actually a major step and a great idea,” says Christoph Wildfeuer, a physicist at Louisiana State University in Baton Rouge who was not involved in the work.
Superposition exists only in the quantum world and is perhaps best known from the example of Schrödinger’s cat. Physicist Erwin Schrödinger proposed a thought experiment in which a cat sits in a closed box along with a radioactive substance that might, or might not, decay and break open a bottle of poison gas. Until the box is opened and its contents are observed, the cat exists in a superposition: it is both alive and dead at the same time.