Molecules finally join the quantum entanglement club

Polar molecules are exquisitely sensitive to electric and magnetic fields — and to exotic new physics — but nobody had managed to entangle them in a metrologically useful way. This experiment traps CaF molecules in an optical tweezer array and exploits their natural dipole-dipole interactions to produce spin-squeezed states with a 3 dB measurement advantage, then parks that entanglement in quiet hyperfine levels where it survives for 100 ms. The result opens a practical route to molecule-based quantum sensors that beat the standard quantum limit.