Figure 1
J. E. Debs [13], used with permission

Figure 1: The principle of operation of a cold-atom accelerometer. The optical ruler is provided by a standing wave. The ruler is imprinted on the freely falling atoms at the input pulse (first beam splitter), mirror pulse, and output beam splitter. Acceleration parallel to the axis of the ruler produces a phase shift that can be measured on the output ports of an atom interferometer.