Ultracold atoms measure gravity with surprising precision

Extremely cold atoms have been used to measure gravity more precisely than we thought possible, beating a limit that stems from quantum weirdness.

Ultracold atoms are some of the most sensitive force sensors. They are useful for such work because at the coldest possible temperature – absolute zero – they take on quantum properties that are extremely susceptible to pushes and pulls in their environment. But that sensitivity can be muddled by the small fluctuations, or “quantum noise”, in the atoms’ states.