NIST's prototype chip for measuring important quantities such as length with quantum precision. The device works by using a laser to probe atoms to generate infrared light at a precise wavelength. The NIST chip packs a tiny cloud of atoms and structures for guiding light waves into less than 1 square centimeter. The atoms are contained in a vapor cell--the square window on top of the chip, which is surrounded by black epoxy holding a fiber-optic array. The penny is a scale reference.