Coherent Atom Transport via Enhanced Shortcuts to Adiabaticity: Double-Well Optical Lattice

Abstract: Theoretical studies of coherent atom transport have as yet mainly been restricted to one-dimensional model systems with harmonic trapping potentials. Here we investigate this important phenomenon -- a prerequisite for a variety of quantum-technology applications based on cold neutral atoms -- under much more complex physical circumstances. More specificially yet, we study fast atomic transport in a moving {\em double-well optical lattice}, whose three-dimensional (anharmonic) potential is nonseparable in the $x-y$ plane. We first propose specific configurations of acousto-optic modulators that give rise to the moving-lattice effect in an arbitrary direction in this plane. We then determine moving-lattice trajectories that enable single-atom transport using two classes of quantum-control methods: shortcuts to adiabaticity (STA), here utilized in the form of inverse engineering based on a quadratic-in-momentum dynamical invariant of Lewis-Riesenfeld type, and their recently proposed modification termed enhanced STA (eSTA). Subsequently, we quantify the resulting single-atom dynamics by numerically solving the relevant time-dependent Schr\"{o}dinger equations and compare the efficiency of STA- and eSTA-based transport by evaluating the respective fidelities. We show that -- except for the regime of shallow lattices -- the eSTA method consistently outperforms its STA counterpart. This study has direct implications for neutral-atom quantum computing based on collisional entangling two-qubit gates and quantum sensing of constant homogeneous forces via guided-atom interferometry.