Mainz 2017 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 31: Poster: Quantum Optics and Photonics I

Q 31.59: Poster

Tuesday, March 7, 2017, 17:00–19:00, P OG1+2

Atom Position Control — •Karl Nicolas Tolazzi, Christoph Hamsen, Tatjana Wilk, and Gerhard Rempe — Max Planck Institute of Quantum Optics, Hans-Kopfermann-Straße 1, 85748 Garching

A strongly coupled single-atom-cavity system is well suited to implement quantum nonlinear optics at the single-photon level. In order to achieve strong coupling with a constant and reproducible coupling strength, the single atom must be well positioned within the cavity mode. In our experiment the atom is held inside the cavity in a three dimensional optical lattice that is formed by a blue-detuned intra-cavity standing wave together with a blue and a red transverse standing wave. Fluorescence light that is emitted during cooling of the atom is collected by a high numerical-aperture objective and detected on a camera. With a single 2 dimensional (2D) image, the 3D position of the atom can be determined using the out-of-focus blur to assess the out-of-plane direction. This allows for measuring the position and extent of the vacuum cavity mode in three dimensions by probing the atom-cavity coupling via normal-mode spectroscopy and post-selecting on specific atom positions. As the standing waves of the transverse traps are movable due to piezo elements on the retro-reflecting mirrors, we are able to control the atom position via feedback. The knowledge of the atom position with respect to the cavity mode and the ability to shift and stabilize its position grant a high and constant coupling strength between them over many experimental cycles and is here shown by reaching an average coupling strength close to the theoretical value.