Integrated Single Atom Detector

Marco Wilzbach

The subject of this thesis is the miniaturization and integration of detectors for the detection of single rubidium atoms on an atom chip. For this purpose three different detectors were developed for atom detection by absorption or fluorescence: i) A fluorescence detector was realized by mounting a tapered lensed fiber perpendicular to a collection fiber. ii) An absorption detector was built by placing a multi-mode fiber in-line with a tapered lensed fiber. iii) A tunable cavity detector was built from two single mode fibers mounted on the chip surface. To mount the detectors on the planar surface of the atom chip retaining structures by means of lithographical techniques were developed. Those structures allow a very accurate and stable passive fiber alignment. To test the individual detectors an atomic ensemble of thermal rubidium atoms was prepared in a magneto-optical trap. Then the atoms were transferred into magnetic micro-traps of the atom chip and were guided to one of the detectors. Each integrated detector has been evaluated by several characterization measurements. With the fluorescence detector the highest single atom detection efficiency of 54\\% was attained. Thereby it was possible to perform quantitative measurements for the magnetically guided atoms on a single atom level and to study fundamental properties of the confined atoms.

Jonas Bergquist, Randall G. Hulet, Wayne M. Itano +1 more

Marco Wilzbach, Dennis Heine, S. Groth +4 more

We present a reliable and robust integrated fluorescence detector capable of detecting single atoms. The detector consists of a tapered lensed single-mode fiber for precise delivery of excitation light and a multimode fiber to collect the fluorescence. Both are mounted in lithographically defined SU-8 holding structures on an atom chip. 87Rb atoms propagating freely in a magnetic guide are detected with an efficiency of up to 66%, and a signal-to-noise ratio in excess of 100 is obtained for short integration times.

G. S. Hurst, Munir Hasan Nayfeh, Jack Phillip Young +2 more

Dennis Heine, Marco Wilzbach, Thomas Raub +2 more

We demonstrate a robust fiber-optics-based fluorescence detector, fully integrated on an atom chip, which detects single atoms propagating in a guide with 66% efficiency. We characterize the detector performance and the atom flux by analyzing the photon statistics. Near-perfect photon antibunching proves that single atoms are detected, and allows us to study the second-order intensity correlation function of the fluorescence over three orders of magnitude in atomic density.

Conny Glaser, Dominik Jakab, Florian Jessen +3 more