Within tiny halos of light clinging to a vanishingly thin wisp of optical fiber, scientist Jongmin Lee guides atoms like marbles through a narrow pipe. Rock the fiber and the atoms shift side by side; they just don’t fall off. But don’t be deceived by the seemingly delicate nature of his experiment. Lee is exploring how to measure motion precisely in rough-and-tumble environments.

A quantum sensing scientist at Sandia National Laboratories, Lee is an expert in a type of motion sensor called an atom interferometer. In a lab, this device uses quantum mechanics to obtain exquisitely accurate measurements. Lee and his team are working toward building an extremely small, low-power version for field use—small enough to fit on a specialized type of microchip called a photonic integrated circuit.

Their latest results were published in the journal AVS Quantum Science, where the team reported trapping cesium atoms on a fiber only 420 nanometers in diameter with just 5 milliwatts of optical power—about 2,000 times less power than an LED bulb uses. With just 150 nanowatts, the researchers can also take measurements that mimic atom interferometry.