Towards a Multi-Minute Lattice Atom Interferometer*

Matter wave interferometry using a spatial superposition of ultracold atoms is a powerful tool for precision metrology. In our lattice atom interferometer, the interrogation time is increased by levitating the atoms in an optical lattice generated by the mode of an optical cavity. Our recent 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 to extend coherence to the multi-minute scale by suppressing tilt-noise in the most vulnerable frequency band with active vibration isolation of the whole mechanical system, as well as by reducing temperature and phase space density through evaporative cooling to below the recoil limit. As a part of this new apparatus, we will also integrate a high-Q, diamagnetic torsion pendulum with the long term goal of generating non classical atom-oscillator states and probing the coherence of gravity.