The strongest form of correlations between particles are those that violate a Bell inequality. We have detected such Bell correlations between 480 atoms in a Bose-Einstein condensate, using a witness inequality that we derived in collaboration with the theory groups of N. Sangouard and V. Scarani.
Dr. Janik Wolters was awarded a Marie-Skłodowska-Curie Fellowship from the European Commission for the project "Cold atom-semiconductor quantum interface" - congratulations! We thank the European Union for the generous support and hope that the project will help to exploit the potential of quantum science to benefit the European economies and societies.
The European Research Council has awarded a Starting Grant to Prof. Philipp Treutlein for the project "Modular mechanical-atomic quantum systems", which is scheduled to start in early 2016. We thank the European Union for generously supporting the Swiss research community.
We record images of microwave fields with sub-100 μm resolution using a microfabricated alkali vapor cell. The setup can additionally image dc magnetic fields, and can be configured to image microwave electric fields. Our technique could prove transformative in the design, characterisation, and debugging of microwave devices and find applications in medical imaging. These results were published in New Journal of Physics 17, 112002 (2015) as a fast track communication.
In collaboration with the Warburton group, we have developed a semiconductor quantum dot single photon source that emits transform-limited photons at 780 nm, the wavelength of the Rubidium D2 line. The quantum dot photons are tuned into exact resonance with hyperfine transitions of natural Rubidium atoms, a key step towards storing them in an atomic quantum memory. These results were published in Phys. Rev. B 92, 245439 (2015)..
We have used ultracold atoms to cool the vibrations of a nanomechanical membrane from room-temperature to 650 mK. While sympathetic cooling with atoms has previously been used to cool other microscopic particles, we extend it to the cooling of an engineered solid-state structure, whose mass is 10 orders of magnitude larger than that of the atoms. These results were published in Nature Nanotechnology 10, 55 (2015). See also the news features in Deutschlandfunk and Telebasel.