A Moving Waveguide Saganc Atom Interferometer

Atom interferometer inertial sensors have several important applications, including improving the performance of inertial navigation in the absence of GPS. A guided atom interferometer, in which the atomic wavepackets are confined inside a waveguide while they move through the interferometer, offers the possibility of obtaining long interrogation times with a compact physics package because the waveguide supports the atoms against gravity and allows for multiple round-trips in the interferometer. We are developing a guided Sagnac atom interferometer for rotation sensing. The waveguide is formed by a collimated red-detuned laser beam. Suitably-shaped Bragg pulses split, reflect, and recombine the wavepackets inside the waveguide. Moving the waveguide during the interferometer cycle makes the atomic trajectories enclose an area which makes the device sensitive to rotations through the Sagnac effect. We obtain high interferometer contrast at total interrogation times of 360 ms, and we have observed interference after the atoms have made three orbits of the Sagnac area, which is a path to increased sensitivity. In that case the total Sagnac area is 9 sq mm. The device is also able to measure rotations about both vertical and horizontal axes without changing the orientation of the sensor, which would require challenging compensation of gravity. The sensitivity of the interferometer is currently limited by technical noise. In this talk we will report on its current status.