The Cold Atoms Lab (CAL) is a compact, atom chip-based facility for examining ultra-cold quantum gases such as Bose-Einstein condensates (BEC). CAL represents a new era in ISS research, as now, for the first time, fundamental physics questions can be investigated with high precision using quantum objects at almost absolute zero (-273.15 degrees Celsius). In this installation, clouds of rubidium and potassium atoms are generated, as well as mixtures of both atom types. The movement of the atoms is slowed down using pulses of laser light. These extremely decelerated atoms are trapped in an atom chip, a magnetic trap. Once the magnetic field is lowered, only the coldest and thus slowest atoms remain in the trap.
With decreasing temperature, very close to absolute zero, the atoms behave like a single 'giant atom' – a Bose-Einstein condensate has now formed. This can now be examined macroscopically. In a state of microgravity on the ISS, BECs have a lifespan of up to 20 seconds. This cannot be achieved in any laboratory on Earth. The longer the BEC can be maintained, the more accurate are the results provided by the macroscopic quantum sensor – here, the sensitivity of an atomic interferometer increases with the square of the lifespan of a BEC. The technical developments that have been strongly advanced for installations such as CAL and BECCAL mean that quantum sensors can also be used outside fundamental research, for example to control the positions of satellites, to control the distances in formation flights of a satellite swarm, or to measure the gravitational fields of Earth or other celestial bodies.