Programmable multidimensional quantum sensing using ultracold atoms in 3D optical lattices*

In this talk, I will present experimental results from a new kind of atom interferometer that uses Bose-Einstein condensed atoms loaded into a 3D lattice. By moving the position of the lattice via either phase or frequency modulation, the traditional steps of interferometry can be implemented; beamsplitting, propagating, reflecting, again propagating and then recombining the atomic wavefunction. This is distinct from traditional light-pulse atom interferometry, since the entire sequence is performed while the atoms are held in the periodic optical potential instead of in free-fall. The position of the lattice is varied according to protocols that are derived via several machine-design methods, including machine learning and quantum optimal control. The resulting protocols constitute gates that we cascade together to carry out quantum operations that encode a variety of sensing circuits. Gates in this context represent input-output matterwave transformations between lattice eigenstates, specifically states in the valence band where the atoms are frozen, and in the conduction band where the atoms can transport. We refer to this novel sensor as a Bloch band interferometer (BBI) since it relies on the underlying lattice band structure. We can create a multitude of different sensing devices in a single hardware platform for the measurement of inertial forces, rotating reference frames, and gravity gradients. Since the functionality is encoded in software rather than hardware, the apparatus design can be programmed on-the-fly to respond to an evolving set of design priorities, such as sensitivity or dynamic range.