Abstract
We demonstrate the ability to load, cool and detect singly charged calcium ions in a surface electrode trap using only visible and infrared lasers for the trapped-ion control. As opposed to the standard methods of cooling using dipole-allowed transitions, we combine power broadening of a quadrupole transition at 729 nm with quenching of the upper level using a dipole allowed transition at 854 nm. By observing the resulting 393 nm fluorescence we are able to perform background-free detection of the ion. We show that this system can be used to smoothly transition between the Doppler cooling and sideband cooling regimes, and verify theoretical predictions throughout this range. We achieve scattering rates which reliably allow recooling after collision events and allow ions to be loaded from a thermal atomic beam. This work is compatible with recent advances in optical waveguides, and thus opens a path in current technologies for large-scale quantum information processing. In situations where dielectric materials are placed close to trapped ions, it carries the additional advantage of using wavelengths which do not lead to significant charging, which should facilitate high rate optical interfaces between remotely held ions.
Highlights
Trapped ions are among the leading candidates for quantum information processing and quantum simulation, as well as being leading contenders for realising accurate atomic clocks
From simulations of the optical Bloch equations (OBEs) for typical parameters of the 854 and 866 nm lasers we find that the probability to exit the cooling cycle for an ion starting in the D5 2, Mj = -5 2 level is between 0.6% and 1.5%, dependent on the 854 nm laser intensity
The results presented above provide evidence that visible and IR lasers can be used to perform all of the common tasks required for quantum information experiments with trapped ions
Summary
Trapped ions are among the leading candidates for quantum information processing and quantum simulation, as well as being leading contenders for realising accurate atomic clocks. The second method involves linking remote ion traps via optical interfaces This can either be performed using free-space photons or using high-finesse optical cavities. Integrated waveguides were recently used to address ions in a micro-fabricated trap using laser light at 670 nm [3], but further work is required before all-optical delivery can be incorporated into trapping structures. For this purpose, it seems desirable to work at wavelengths in the visible and infra-red (IR) regions of the spectrum, where technologies for integrated optics are relatively mature
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