Researchers in Singapore have built a refrigerator that’s just three atoms big.

This quantum fridge won’t keep your drinks cold, but it’s cool proof of physics operating at the smallest scales. The work is described in a paper published in Nature Communications (“Quantum absorption refrigerator with trapped ions”).

Researchers have built tiny ‘heat engines’ before, but quantum fridges existed only as proposals until the team at the Centre for Quantum Technologies at the National University of Singapore chilled with their atoms.