The workshop “Quantum Systems in Free Fall” (website) took place from 6th to 8th of May 2025 at the Center of Applied Space Technology and Microgravity (ZARM) of the University of Bremen, Germany. The workshop was organised jointly by two COST Actions: BridgeQG (CA23130, Bridging high and low energies in search of quantum gravity) and RQI (CA23115, Relativistic Quantum Information). Tomislav Terzić participated as a member of the International Programme Committee. Christian Pfeifer, who has since joined our team, was one of the local organisers. During his stay in Bremen, Tomislav Terzić also gave a seminar at ZARM.

The workshop brought together experimentalists and theoreticians working on the interface of quantum mechanics and gravity. Different models predict different behaviour of quantum systems in free fall, so observing such systems can reveal information about the structure of spacetime. The discussions focused on which aspects of the theoretical models can be tested in realistic free-fall experiments, such as matter-wave interferometry in the ZARM drop tower, and what technical specifications such experiments would need.