We present a method for determining the phase and contrast of a single shot of an atom interferometer. The application of a phase shear across the atom ensemble yields a spatially varying fringe pattern at each output port, which can be imaged direct
ly. This method is broadly relevant to atom interferometric precision measurement, as we demonstrate in a 10 m Rb-87 atomic fountain by implementing an atom interferometric gyrocompass with 10 millidegree precision.
We show that light-pulse atom interferometry with atomic point sources and spatially resolved detection enables multi-axis (two rotation, one acceleration) precision inertial sensing at long interrogation times. Using this method, we demonstrate a li
ght-pulse atom interferometer for Rb-87 with 1.4 cm peak wavepacket separation and a duration of 2T = 2.3 seconds. The inferred acceleration sensitivity of each shot is 6.7 * 10^(-12) g, which improves on previous limits by more than two orders of magnitude. We also measure the Earths rotation rate with a precision of 200 nrad/s.
