Controlling trapping potentials and stray electric fields in a microfabricated ion trap through design and compensation

Abstract

Recent advances in quantum information processing with trapped ions have\ndemonstrated the need for new ion trap architectures capable of holding and\nmanipulating chains of many (>10) ions. Here we present the design and detailed\ncharacterization of a new linear trap, microfabricated with scalable\ncomplementary metal-oxide-semiconductor (CMOS) techniques, that is well-suited\nto this challenge. Forty-four individually controlled DC electrodes provide the\nmany degrees of freedom required to construct anharmonic potential wells,\nshuttle ions, merge and split ion chains, precisely tune secular mode\nfrequencies, and adjust the orientation of trap axes. Microfabricated\ncapacitors on DC electrodes suppress radio-frequency pickup and excess\nmicromotion, while a top-level ground layer simplifies modeling of electric\nfields and protects trap structures underneath. A localized aperture in the\nsubstrate provides access to the trapping region from an oven below, permitting\ndeterministic loading of particular isotopic/elemental sequences via\nspecies-selective photoionization. The shapes of the aperture and\nradio-frequency electrodes are optimized to minimize perturbation of the\ntrapping pseudopotential. Laboratory experiments verify simulated potentials\nand characterize trapping lifetimes, stray electric fields, and ion heating\nrates, while measurement and cancellation of spatially-varying stray electric\nfields permits the formation of nearly-equally spaced ion chains.\n