The heart of a minuscule atomic clock---believed to be 100 times smaller than any other atomic clock---has been demonstrated by scientists at the Commerce Department's National Institute of Standards and Technology (NIST), opening the door to atomically precise timekeeping in portable, battery-powered devices for secure wireless communications, more precise navigation and other applications. Described in the Aug. 30, 2004, issue of Applied Physics Letters, the clock's inner workings are about the size of a grain of rice (1.5 millimeters on a side and 4 millimeters high), consume less than 75 thousandths of a watt (enabling the clock to be operated...
