Surface-electrode ion trap with integrated light source

An atomic ion is trapped at the tip of a single-mode optical fiber in a cryogenic (8 K) surface-electrode ion trap. The fiber serves as an integrated source of laser light, which drives the quadrupole qubit transition of \(^{88}\)Sr\(^+\). Through \emph{in situ} translation of the nodal point of the trapping field, the Gaussian beam profile of the fiber output is imaged, and the fiber-ion displacement, in units of the mode waist at the ion, is optimized to within \(0.13\pm0.10\) of the mode center despite an initial offset of \(3.30\pm0.10\). Fiber-induced charging at \(125 \mu\)W is observed to be \({\sim}10\) V/m at an ion height of \(670 \mu\)m, with charging and discharging time constants of \(1.6\pm0.3\) s and \(4.7\pm0.6\) s respectively. This work is of importance to large-scale, ion-based quantum information processing, where optics integration in surface-electrode designs may be a crucial enabling technology.