These days, cats still don’t act this way, but physicists now regularly create analogues of Schrödinger’s cat in the lab by smearing the microscopic quantum world over longer and longer distances.
Such “Cat states” have found many homes, promising more sensitive quantum measurements and acting as the basis for quantum error-correcting codes-a necessary component for future error-prone quantum computers.
With these goals in mind, some researchers are eager to create better cat states with single ions.
So far, standard techniques have imposed limits on how far their quantum nature could spread. Recently, researchers at the Joint Quantum Institute developed a new scheme for creating single-ion cat states, detailing the results this week in Nature Communications.
Their experiment places a single ytterbium ion into a superposition-a quantum combination-of two different states. There’s still just one ion, but its quantum nature now extends over a distance more than a thousand times larger than its original size.
Such long-range superpositions are highly sensitive, and could enable precise atom interferometry measurements or robust quantum cryptographic techniques.