Mainz 2026 – scientific programme

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A: Fachverband Atomphysik

A 36: Poster – Ultra-cold Atoms, Ions and BEC (joint session A/Q)

A 36.15: Poster

Thursday, March 5, 2026, 17:00–19:00, Philo 1. OG

Towards Autonomous Optical Alignment for NV-Center and SHG Experiments — •Zhen Mi, Tobias Spanke, Frederike Dörr, Jörn Denter, Ulrich Warring, and Tobias Schätz — Physikalisches Institut, Albert-Ludwigs-Universität, Freiburg

We present an automated beam-alignment framework designed for optical experiments requiring long-term stability, in particular NV-center excitation/collection paths and second-harmonic generation (SHG) stages. Stable and reproducible alignment is essential for maintaining photon rates, SHG efficiency, and experimental reliability, yet manual alignment suffers from drift, operator dependence, and time overhead. Our approach combines motorized mirror mounts, in-loop detectors, and gradient-free optimization routines to autonomously explore multi-parameter alignment spaces. We benchmark the system on NV-center fluorescence collection and SHG cavity coupling. The automated routines consistently improve alignment quality, reduce sensitivity to mechanical and thermal drifts, and increase reproducibility across repeated optimization cycles. We further analyze critical aspects such as distinguishing signal drift from noise, managing low-SNR conditions, and maintaining robustness over long measurement sequences. These results lay the groundwork for self-calibrating optical experiments and scalable, low- maintenance optical setups for quantum sensing and nonlinear optics.

Keywords: Automated alignment; SHG; NV centers; Nonlinear opti; Ions