Flannery, Jeremy

Date:   Monday, December 16, 2019
Time:   11:00
Place:   ETH Zurich, Hönggerberg, HPF G 6
Host:    Jonathan Home

Optical Resonators Integrated into a Hollow Core Photonic Crystal Fiber for Enhanced Light-Matter Interactions

Jeremy Flannery
University of Waterloo, Canada

Hollow-core fibers loaded with atomic ensembles offer a platform for strong light-matter interactions, with experimental demonstrations in recent years including all-optical switching, cross-phase modulation with few photons, and single-photon broadband quantum memory. Further enhancement of these light-matter interactions can be accomplished by incorporating a cavity into the fiber and we realized such cavities by attaching photonic crystal membranes acting as mirrors to the ends of a hollow-core photonic crystal fiber (HCPCF) segment. More recently, we designed and fabricated our photonic-crystal mirrors to be polarization dependent — highly reflective for one linear polarization but with almost full transmission for the orthogonal polarization — using a pattern with broken Cartesian symmetries. Such a unique type of polarization-dependent fiber-integrated cavity may enable experimental schemes in which light signals with the appropriate polarization can be sent co-propagating to interact with the atomic cloud either in a single pass as if the cloud was in free space, or be enhanced by the cavity. Based on such fiber-integrated cavities with cold atoms loaded into a hollow-core optical fiber, we propose a novel scheme for an all-optical switch for single photons. Our proposal employs a single photon probe field and a vacuum cavity mode coupled to an ensemble of three-level atoms with two metastable ground states. In our scheme, we set the coupling cavity and probe fields to the far detuned Raman regime. However, because we use a vacuum cavity mode as a coupling field, this may be referred to as a vacuum induced Raman absorption (VIRA), which can have a characteristically narrow linewidth. Setting the probe photon frequency to this VIRA resonance, the optical switch can then be activated by injecting a single gate photon into the cavity mode, shifting the VIRA resonance such that the probe field is instead off resonance allowing for large transmission.