Manipulating atoms into quantum entangled states is hard enough, but then proving that you have achieved that entanglement is harder still. But that is the goal of an experiment at the Institute for Quantum Optics and Quantum Information (IQOQI) in Vienna, as explained in this interview with physicist Michael Keller – recorded before the COVID-19 pandemic.

Keller’s team is seeking to create momentum-entangled particles by cooling helium atoms into a Bose-Einstein condensate and “kicking” them with lasers. As observing entangled states directly tends to destroy the entanglement, the researchers have devised indirect methods for study the helium atoms’ properties. The group’s long-term goal is to carry out tests on these momentum-entangled states to probe the foundations of quantum physics.