NIST physicists John Bollinger (left) and Matt Affolter adjust the laser and optics array used to trap and probe beryllium ions in the large magnetic chamber (white pillar at left). The ion crystal may help detect mysterious dark matter. Crossed laser beams were used to entangle the collective spin with the motion. The same lasers and microwaves were used to undo the entanglement. The experiment benefited from a collaboration with NIST theorist Ana Maria Rey, who works at JILA.