Nothing is more adorable than a kitten playing with string, but when Schrödinger’s cat becomes entangled, things get really weird.
Two research teams have independently added an extra layer of quantum oddity – the property of entanglement – to a test of wave-particle duality, a real-life demonstration of the ideas captured by physicist Erwin Schrödinger’s famous thought experiment involving a box and a precarious puss.
This extra layer of entanglement lets the researchers delay measuring the results of the test for an indefinite amount of time, even though the measurement itself is supposed to have determined earlier on whether a photon is behaving as a particle or a wave at a particular point in the experiment. It’s the equivalent of putting off the decision to check whether Schrödinger’s cat is alive, dead or something in between, for as long as you like.
Understanding this doubly quantum effect could be useful when building quantum computers and communication networks, which depend on entanglement to function.