Mainz 2026 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 14: Poster – Precision Spectroscopy of Atoms and Ions (joint session A/Q)

A 14.13: Poster

Dienstag, 3. März 2026, 17:00–19:00, Philo 1. OG

Frequency Stabilization of a 1762 nm Diode Laser for Quantum Logic Spectroscopy of Barium Ions — •Han Bap, Alexander Windt, Wei Wu, and Tobias Schaetz — Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Straße 3, 79104 Freiburg, Germany

We report on the implementation of a frequency stabilization system for a 1762 nm diode laser, a key component for advanced experiments with trapped Barium ions 138Ba+. This laser wavelength is critical for exciting the ions from the 6S1/2 ground state to the long-lived metastable 5D5/2 state, a necessity for resolve sideband cooling and phonon number measurement. To achieve the required long-term spectral stability and narrow linewidth, we have locked the laser to a high-finesse, ultra-low expansion (ULE) glass cavity using the Pound-Drever-Hall (PDH) technique. We will show the detailed the laser system design, the characterization of the ULE reference cavity, and the implementation of the PDH locking electronics. We present a performance analysis demonstrating a locked linewidth of < 1 kHz and long-term frequency drift of < 0.1 MHz/hour. This stable 1762 nm source is a cornerstone for our ongoing work on quantum logic spectroscopy of the Barium ion's narrow optical quadrupole transition, paving the way for improved study of atom-ion collision between Barium and Rubidium.

Keywords: Barium ions; frequency stabilization