Josef U. Fürst

TL;DR: In this paper, a combination of frequency analysis and far-field imaging for high mode numbers of large whispering-gallery mode resonators is proposed to identify the radial mode numbers q and the angular mode numbers p = l-m.

TL;DR: It is shown experimentally that the modal structure and quality factors are similar to common resonators but that the polarization properties differ quite significantly: due to the asymmetry the polarization depends on the equatorial position and is, in general, elliptical.

TL;DR: A fiber-based continuous-variable quantum key distribution system that witness effective entanglement with a channel length of up to 2 km and the local oscillator is considered in the verification.

Abstract: We demonstrate a method to perform spectroscopy of near-infrared single photons without the need of dispersive elements. This method is based on a photon energy resolving transition edge sensor and is applied for the characterization of widely wavelength tunable narrow-band single photons emitted from a crystalline whispering gallery mode resonator. We measure the emission wavelength of the generated signal and idler photons with an uncertainty of up to 2 nm.

TL;DR: Whispering gallery resonators made from crystalline materials are compact, stable and highly tunable as discussed by the authors, showing promise for applications in spectroscopy, metrology and quantum information schemes.