Paper detail

Doppler-free, Multi-wavelength Acousto-optic deflector for two-photon addressing arrays of Rb atoms in a Quantum Information Processor

We demonstrate a dual wavelength acousto-optic deflector (AOD) designed to deflect two wavelengths to the same angles by driving with two RF frequencies. The AOD is designed as a beam scanner to address two-photon transitions in a two-dimensional array of trapped neutral Rb atoms in a quantum computer. Momentum space is used to design AODs that have the same diffraction angles for two wavelengths (780 nm and 480 nm) and have non-overlapping Bragg-matched frequency response at these wavelengths, so that there will be no crosstalk when proportional RF frequencies are applied to diffract the two wavelengths. The appropriate crystal orientation, crystal shape, transducer size, and transducer height are determined for an AOD made with a Tellurium dioxide crystal (TeO2). The designed and fabricated AOD has more than 100 resolvable spots, widely separated bandshapes for the two wavelengths within an overall octave bandwidth, spatially overlapping diffraction angles for both wavelengths (780 nm and 480 nm), and a 4 usec or less access time. Cascaded AODs in which the first device upshifts and the second downshifts allow Doppler-free scanning as required for addressing the narrow atomic resonance without detuning. We experimentally show the diffraction-limited Doppler-free scanning performance and spatial resolution of the designed AOD.