GoKawiilPhysicists detect single molecular ion's vibrations using ultra-sensitive quantum sensor
Researchers built a two-ion crystal in a Paul trap combining a calcium ion with a single CaOH+ molecular ion, generated by leaking water vapor into the vacuum chamber until a molecule formed. They then used a non-classical 'cat state' of motion, created with a bichromatic laser on the calcium ion, to detect the tiny photon recoil from the molecule absorbing infrared light—effectively performing infrared absorption spectroscopy on one single polyatomic molecular ion.