Interview with Tommaso Calarco
Jülich, 8 March 2021 – Quantum physicist Tommaso Calarco from Forschungszentrum Jülich is a specialist in optimising quantum processes. Together with researchers from TU Wien, he has now achieved a feat that was previously only possible with photons: the controlled production of quantum entangled atomic beams. In an interview, he explains the potential applications of the new method.
Professor Calarco, last week you published a new speed limit for the transport of quantum information with atoms. Shortly afterwards, your study on the entanglement of atoms appeared – a coincidence?
Yes, it is indeed pure coincidence that these two results have now emerged almost simultaneously. These experiments in Vienna were also preceded by years of preparation. The crucial point is that we succeeded in entangling not just individual atoms, but really a large number of atoms and emitting them in a targeted manner. Although the atoms move away from each other, their state continues to depend on each other due to quantum entanglement. Until now, this was only possible with photons.
What opportunities does the new method open up?
In principle, of course, this is first of all a result of basic research. On the one hand, one obviously wants to realise analogous systems as with light, with the aim of realising the phenomena with a different system, namely with atoms. On the other hand, there are already atomic lasers that generate coherent beams with atoms that all have the same speed and move coherently. There are applications for this in interferometry, for example, where tiny fields are measured. In principle, this makes extremely accurate sensors possible, for example for navigation systems, which could be further improved by entanglement. In addition, atoms have different properties than photons.
What is so special about atoms?
Photons, for example, have no mass. They don't care about gravity at all, so you can't use them directly to measure gravity. But with atoms this would be possible because they have a mass; and with coherent mass states in the form of entangled atoms, gravity could be measured even more precisely. There is a French quantum start-up, Muquans, which is already developing gravimeters based on atoms. So far, they don't use entanglement, but I'm pretty sure that with entangled atoms you would have additional advantages.