Introduction
Neutral atoms coupled to high-finesse optical cavities provide unique systems to study interactions of light and matter in the quantum regime. While photons are excellent carriers of quantum states for large distance transmission, the long coherence times of trapped ultracold atoms are optimal for the storage of quantum information. The strong coupling achievable in our cavity quantum electrodynamics (cavity QED) systems make them ideally suited for the implementation of deterministic quantum interfaces.
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 Position
If you are interested in joining our team as a PhD student, have a look at the
job description.
Highlights
April 2012: "
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.
May 2011: "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.
February 2011: In a joint effort, the BEC and Pistol teams have managed to create remote entanglement between a single atom and a Bose-Einstein condensate, situated in two independent labs separated by 13m. The fidelity with a maximally entangled Bell state is 95% and the matter-matter entanglement survives for 100µs. Details can be found in
our paper.
January 2011: We welcome
Manuel Uphoff as a new PhD student in our team. Manuel successfully finished his diploma thesis entitled " State manipulation of single atoms in an optical cavity" in February 2010.
Dezember 2010: Holger Specht was awarded his Ph.D for his work on "Einzelatom-Quantenspeicher für Polarisations-Qubits".
November 2010: Our efforts towards establishing single atoms in optical resonators as a platform for a
quantum repeater are now funded by the
Bundesminsterium für Bildung und Forschung (BMBF).
July 2010: Jörg Bochmann was awarded his Ph.D for his work on "Coherent Dynamics and State Detection of Single Atoms in a cavity".
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.
May 2010: "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).
March 2010: MPQ made up of a single atom! The QGate team can position their single atom with micrometer precision inside the cavity. Adding storage times of 70 seconds, fun and creativity, the MPQ logo can be "written" by recording the fluorescence of a single atom. Vertical axis: position of the atom. Horizontal axis: time. (click to enlarge)
March 2010: Christoph Guhl is awarded his diploma in Physics.
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.
November 2008: Bernhard Weber awarded his Ph.D for his work on "Distribution of Quantum Information between an Atom and Two Photons".
May 2008: David Moehring receives 2008 DAMOP Thesis Prize from the American Physical Society.
February 2008: Tatjana Wilk awarded her Ph.D for her work on the "Quantum Interface between an Atom and a Photon".
A Sisyphean Task for Polar Molecules
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