Their study used a sophisticated setup involving superconducting devices, known as traps, with magnetic fields, sensitive detectors and advanced vibration isolation. It measured a weak pull, just 30aN, on a tiny particle 0.43mg in size by levitating it in freezing temperatures a hundredth of a degree above absolute zero—about –273 degrees Celsius.
Good god, this sounds like a difficult experiment to pull off. Thirty atto-Newtons. You don't hear atto-anything very often.