Quantum Squeezing of Molecules Improves Sensor Accuracy Threefold ⚡ экспресс
Ultra-precise measurements with polar molecules have long been hindered by the lack of metrologically useful entangled states. This work realizes spin-squeezed states for the first time in an optical tweezer array of CaF molecules, where spin degrees of freedom are encoded in rotational levels coupled by dipolar exchange interactions. Using dynamical decoupling and Floquet engineering, a metrological gain of up to 3.0(3) dB (2.2(3) dB without measurement correction) was achieved, corresponding to enhanced sensitivity to both homogeneous and spatially inhomogeneous fields. Site- and spin-resolved measurements revealed nonclassical correlations, including bipartite entanglement and Einstein-Podolsky-Rosen steering. The squeezed states were transferred to long-lived, non-interacting hyperfine levels, where metrological enhancement persisted for up to 100 ms. These results turn molecular optical tweezers into a scalable platform for generating, controlling, and storing entangled states, paving the way toward quantum-enhanced sensors and precision tests of fundamental physics.
Any measuring device is spoiled by quantum noise—the chaotic jitters of elementary particles. To tame it, physicists used a trick on calcium fluoride molecules, much like squeezing a balloon: press in one spot, and it bulges in another. The idea is the same: quantum uncertainty is driven into a parameter that doesn't matter for the measurement, while the quantity of interest becomes three times more precise.
The molecules were held in traps made of laser light, made to spin in unison like tiny tops. Using laser pulses and clever light control, scientists built up their entanglement—the very phenomenon Einstein called 'spooky'. Remarkably, the squeezed state was written onto the molecule's internal rotation, where it lasted 100 milliseconds. It's like putting a quantum 'secret' into a safe. Now such molecular sensors can search for dark matter, test laws beyond known physics, and pick up gravitational waves.
🎯 Until now, quantum squeezing had only been achieved with single atoms or ions; molecules—much more complex objects—have been used for the first time.