Quirky cooling: The quantum fridge

When cold milk is poured into a hot cup of tea, a temperature equilibrium is reached very quickly. The milk droplets and the tea particles interact, and after a few moments they all have the same average energy. This process is called thermalization. It plays a crucial role in cooling down gases to ultra-low temperatures. But surprisingly, even gases for which this effect is suppressed can be cooled. Scientists took a closer look at this phenomenon and found a special quantum-mechanical kind of