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Q: Fachverband Quantenoptik und Photonik

Q 35: Poster I

Q 35.70: Poster

Dienstag, 19. März 2013, 16:00–18:30, Empore Lichthof

Laser stabilization to a frequency comb for an optical clock — •Nils Scharnhorst, Jannes B. Wübbena, Sana Amairi, and Piet O. Schmidt — QUEST Institute of Experimental Quantum Metrology, Physikalisch-Technische Bundesanstalt and Leibniz Universität Hannover, Bundesallee 100, D-38116 Braunschweig, Germany

The goal of our project is to build a transportable optical clock based on a single aluminium ion using quantum logic spectroscopy with a co-trapped calcium ion [1]. We give an overview of our clock and the required lasers for laser cooling and clock interrogation. Laser frequency stabilisation is performed by phase-locking all lasers to an optical frequency comb. The repetition rate of the frequency comb can either be locked to a maser, which is referenced to the caesium fountain at PTB, or to a cavity-stabilized laser. The beat signal between the frequency comb and each laser contains the noise of the offset beat, which is fundamentally limited by the feedback bandwidth to the frequency comb. In our scheme the offset beat is electronically subtracted from the beat signals, thus eliminating its noise contribution [2]. The repetition rate can be tightly locked to the reference signal through an intra-cavity electro-optical modulator in the frequency comb's oscillator.

For the stabilization of a laser to the frequency comb a combination of a phase-frequency comparator for slow frequencies and a PI-controller for fast frequencies improves the long-term stability of our laser-lock.

[1] P. O. Schmidt et al., Science 309, 749-752 (2005).

[2] J. Stenger et al., Phys. Rev. Lett. 88, 073601 (2002).