Erlangen 2018 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 62: Poster: Quantum Optics and Photonics V

Q 62.58: Poster

Thursday, March 8, 2018, 16:15–18:15, Redoutensaal

Optical Heterodyne Detection of a Cross-Phase Modulation Mediated by a Single Atom — •Jonas Neumeier, Nicolas Tolazzi, Bo Wang, Gang Li, Tatjana Wilk, and Gerhard Rempe — Max Planck Institute of Quantum Optics, Hans-Kopfermann-Straße 1, 85748 Garching

Controlled interactions between individual photons are of fundamental interest. Cavity quantum electrodynamics in the regime of strong light-matter coupling provides a promising platform for implementing nonlinear interactions. In our experiment, two separate transitions of a four level atom in an N-type scheme are strongly-coupled to two distinct modes of a cavity that are driven by light fields at wavelengths 780 nm and 795 nm. A control laser induces coupling between these modes resulting in either mutual blocking or conjunct tunnelling of photons. Moving one of the modes to the dispersive regime makes non-destructive all-optical sensing of the photon number feasible [1]. It can be understood as the result of a photon number dependent Stark shift [2]. In addition, cross-phase modulation is expected: single photons present in one mode induce a significant phase shift on photons in the other mode. Recently, an optical heterodyne detection setup has been added to the experiment, making the measurement of this cross-phase modulation reachable. The setup combines analog downmixing with FPGA assisted data acquisition, offering direct digitization of both quadratures at a relatively low data rate.
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