Controllable double-well optical trap for cold atoms or molecules and its one-dimensional and two-dimensional optical lattices

Abstract

We propose a novel, to our knowledge, scheme to form a controllable double-well optical dipole trap for cold atoms (or molecules) by using an optical system composed of a binary pi-phase plate and a lens illuminated by a plane light wave. We calculate the intensity distribution of the double-well trap and derive the analytical relationships between the characteristic parameters of the double-well trap (including geometric parameters, intensity distributions, and intensity gradients and their curvatures) and the relative aperture beta of the lens system. We also extend our controllable double-well trap to its trap array by using a binary pi-phase grating combined with an array of spherical microlenses. Our study shows that, if the pi-phase plate (or the pi-phase grating) is moved along the x direction, our double-well trap (or array of double-well ones) can continuously evolve to a single-well one (or an array of single-well ones) and vice versa, which can be used to study cold collisions between two atomic (or molecular) samples and atom interference with Bose-Einstein condensation (BEC) in a double-well potential; to prepare quantum entanglement between two macroscopic atomic assembles, even to realize an all-optical double-well atomic (molecular) BEC (including an array of all-optical double-well BECs) by using optical-potential evaporative cooling; to form a novel optical lattice with a larger lattice constant; and so on.