Tunable axial potentials for atom chip waveguides

We present a method for generating precise magnetic potentials that can be described by a polynomial series along the axis of a cold atom waveguide near the surface of an atom chip. With a single chip design consisting of several wire pairs, various axial potentials can be created by varying the ratio of the currents in the wires, including double wells, triple wells, and pure harmonic traps with suppression of higher order terms. We use this method to design and fabricate a chip with modest experimental requirements. Finally, we use the chip to demonstrate a double well potential.