How to Stop a Nanosphere

To test the limits of quantum physics, researchers would like to see macroscopic objects like nanoscale glass beads exhibiting some of the quantum weirdness familiar from atoms and sub-atomic particles. The first step is to eliminate most of the random thermal motion of such particles. Now a team has gotten close to this goal with a technique that combines two technologies—a charged-particle trap and an optical cavity—to “chill” the motion of a solid nanosphere to the equivalent of 10 degrees above absolute zero. By modifying the cavity, the researchers say they could go further, reducing the motion enough to use a nanosphere to test quantum mechanics, as well as make highly sensitive measurements of gravity.