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Q: Fachverband Quantenoptik und Photonik

Q 31: Poster: Quantum Optics and Photonics I

Q 31.40: Poster

Dienstag, 7. März 2017, 17:00–19:00, P OG1+2

Evaluation of a sub-hertz cavity for an ²⁷Al⁺ optical frequency standard — •Lennart Pelzer¹, Stephan Hannig¹, Johannes Kramer¹, Nils Scharnhost¹, Steven King¹, and Piet O. Schmidt^1,2 — ¹Physikalisch-Technische Bundesanstalt, 38116 Braunschweig — ²Leibniz Universität Hannover, 30167 Hannover

We present a 39.5 cm long ULE cavity for the stabilisation of a 1070 nm laser. After two frequency doubling stages, the light will probe the ¹S₀ ↔ ³P₀ clock transition of a trapped Al⁺ ion, which has a natural linewidth of 2π × 8 mHz. To achieve the necessary level of stability to resolve such a narrow transition, environmental perturbations to the cavity length have to be minimised. A long ULE spacer together with mirrors having a large radius of curvature suppresses the contribution of Brownian thermal noise, which poses the most fundamental limit to the achievable stability, to an estimated fractional level of 7 × 10⁻¹⁷. Especially for such a long cavity spacer, vibration-induced deformations have to be cancelled by exploiting symmetries in the spacer. The evaluation of stability-limiting effects shows the progress in suppressing all relevant noise sources below the thermal noise limit.