Properties of a Rare-Earth-Ion-Doped Waveguide at Sub-Kelvin Temperatures for Quantum Signal Processing.
We characterize the 795 nm ^{3}H_{6} to ^{3}H_{4} transition of Tm^{3+} in a Ti^{4+}:LiNbO_{3} waveguide at temperatures as low as 800 mK. Coherence and hyperfine population lifetimes-up to 117  μs and 2.5 h, respectively-exceed those at 3 K at least tenfold, and are equivalent to those observed in a bulk Tm^{3+}:LiNbO_{3} crystal under similar conditions. We also find a transition dipole moment that is equivalent to that of the bulk. Finally, we prepare a 0.5 GHz-bandwidth atomic frequency comb of finesse >2 on a vanishing background. These results demonstrate the suitability of rare-earth-ion-doped waveguides created using industry-standard Ti indiffusion in LiNbO_{3} for on-chip quantum applications.
Institute for Quantum Science and Technology, and Department of Physics & Astronomy, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
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Sinclair
Institute for Quantum Science and Technology, and Department of Physics & Astronomy, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
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Oblak
Department of Physics, Montana State University, Bozeman, Montana 59717, USA.
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Thiel
Department of Physics, Montana State University, Bozeman, Montana 59717, USA.
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Cone
Institute for Quantum Science and Technology, and Department of Physics & Astronomy, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
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Tittel