What is an atomic clock and how does it work?
If you have read How GPS Receivers Work , you know that atomic clocks are extremely important to the system. You also frequently hear about atomic clocks in ads for the new clocks that automatically synchronize themselves with the atomic clock in Boulder, Colorado. Atomic clocks are also important to a variety of scientific endeavors. So let’s start with the general notion of a clock. A clock’s job is to keep track of the passage of time. All clocks do this by counting the “ticks” of a “resonator.” In a pendulum clock , the resonator is a pendulum and the gears in the clock keep track of time by counting the resonations (the swingings back and forth) of the pendulum. The pendulum usually resonates at a frequency of one swing per second. A digital clock uses either the oscillations on the power line (60 cycles per second in the United States, 50 cycles per second in Europe) or the oscillations of a quartz crystal as the resonator, and counts using digital counters. The accuracy of the c
