Progress Towards a Multi-Minute Lattice Atom Interferometer

Matter wave interferometry using a spatial superposition of ultracold atoms is a powerful tool for precision metrology. A promising instance of this technique is lattice atom interferometry, where the measurement time is increased by levitating atoms in an optical lattice, generated, for instance, by the mode of an optical cavity. Our demonstrations of minute scale spatial coherence in a lattice atom interferometer have shown that decoherence is caused by ensemble dephasing of the thermal atoms in the presence of tilt-noise. We are constructing a new experiment which will enhance performance by suppressing tilt-noise with active vibration isolation of both the vacuum chamber and cavity mirrors, as well as by reducing temperature and phase space density through evaporative cooling further below the recoil limit. Together, these upgrades could enable unprecedented sensitivity and fundamental physics tests using localized source masses. In particular, by integrating a lattice atom interferometer with a diamagnetic, high-Q torsion pendulum, we could generate macroscopic entangled states and ultimately probe the coherence of the gravitational force.