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 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 +/- 0.10 of the mode center despite an initial offset of 3.30 +/- 0.10. Fiber-induced charging by 125 mu W of 674 nm light is observed to be similar to 10 V/m at an ion height of 670 mu m, with charging and discharging time constants of 1.6 +/- 0.3 s and 4.7 +/- 0.6 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. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3593496]