Quantum Information Processing
Our setups allow for full control over an atom residing inside a cavity as well as over all optical fields to which the atom is exposed. With these tools for quantum engineering at hand, we routine produce streams of single photons, whose shape, frequency, direction, polarization, and phase can independently be controlled. The cavity not only serves as an integral part of the photon creation process but also allows for the efficient and in principle deterministic emission into a well defined spatial mode. The coupling mechanism based on cavity QED allows for the creation of atom-photon and photon-photon entanglement with high fidelity, proven via full quantum-state tomography and also the violation of a Bell inequality.
Atom-cavity systems are naturally at the heart of intriguing concepts for quantum computing and quantum communication. Our goal is to realize scalable entanglement protocols and to demonstrate the building blocks of a distributed quantum network.
Open PositionIf you are interested in joining our team as a PhD student, have a look at the job description.
An elementary quantum network of single atoms in optical cavities" by Stephan Ritter et al. has been published in Nature. More information for the general audience can be found in our press release and on the websites of Science, Scientific American and IEEE Spectrum. Spektrum der Wissenschaft and Deutschlandfunk report in German.
March 2012: Manuel Uphoff wins best poster award at the YAO 2012 conference in Krakow, Poland.
"A single-atom quantum memory" by Holger Specht et al. has been published in Nature. The QGate team has realized the most fundamental implementation of an optical quantum memory: Arbitrary polarization states of light can be mapped into and out of a single atom trapped inside an optical cavity, achieving an average fidelity of 93% and storage times of more than 180µs. More information for the general audience can be found in our press release.
June 2010: The paper "Electromagnetically induced transparency with single atoms in a cavity" by M. Mücke et al. has now been published in the print version of Nature. Read the related News & Views article "Single-atom transistor for light" by Scott Parkins in the same issue. He says: "A subtle quantum-interference effect has been used to control the optical response of a single atom confined in a cavity. It could offer a means to develop logic gates for an optical quantum computer."
May 2010: The QGate-Team presented their lab to visitors at the "Lange Nacht der Wissenschaft". (click here for a picture)
May 2010: "Lossless State Detection of Single Neutral Atoms " by J. Bochmann et al, published in Physical Review Letters.
"Electromagnetically induced transparency with single atoms in a cavity" by M. Mücke et al, published online in Nature. Read the press release. Independent articles appeared in the Frankfurter Allgemeine Zeitung (FAZ) (in German), on IEEE spectrum and physicsworld.com (both in English), on spektrumdirekt.de and pro-physik.de (both in German).
February 2010: We welcome Andreas Reiserer in our team. Andreas did his diploma work in the group of Prof. Tobias Brixner (Universität Würzburg) and is now starting his PhD in our group.
August 2009: We welcome Carolin Hahn in our team. Carolin did her diploma work at the Lehrstuhl für Laserspektroskopie (LMU Munich) and is now starting her PhD in our group.
July 2009: "Phase shaping of single-photon wave packets" by Holger Specht et al. published in Nature Photonics. See also the News and Views article by Sean Barrett in the same issue.
June 6, 2009: Holger Specht wins Outstanding Poster Prize at the Quantum Optics VII conference in Zakopane, Poland.
April 2009: Eden Figueroa receives Alexander von Humboldt Foundation research fellowship.
January 2009: "Photon-Photon Entanglement with a Single Trapped Atom" by Bernhard Weber et al. published in Physical Review Letters. Selected for the February 2009 issue of Virtual Journal of Quantum Information.
November 26, 2008: "Fast Excitation and Photon Emission of a Single-Atom-Cavity System" by Jörg Bochmann et al. published in Physical Review Letters.
May 2008: David Moehring receives 2008 DAMOP Thesis Prize from the American Physical Society.