By directly measuring the spin correlations between spatially separated parts of a spin-squeezed Bose-Einstein condensate we observe entanglement that is strong enough for Einstein-Podolsky-Rosen steering: We can predict measurement outcomes for noncommuting observables in one spatial region on the basis of corresponding measurements in another region with an inferred uncertainty product below the Heisenberg uncertainty bound. This method could be exploited for entanglement-enhanced imaging of electromagnetic field distributions and quantum information tasks. The results were reported in Science 360, 409-413.
We have observed the effects of collective atomic motion in a one-dimensional optical lattice coupled to an optomechanical system. In this hybrid atom-optomechanical system, the lattice light generates a coupling between the lattice atoms as well as between atoms and a micromechanical membrane oscillator. For large atom numbers we observe an instability in the coupled system, resulting in large-amplitude atom-membrane oscillations. We show that this behavior can be explained by light-mediated collective atomic motion in the lattice. These results were published in Physical Review Letters 120, 073602.
We have demonstrated a quantum memory in warm Rb vapor with on-demand storage and retrieval, based on electromagnetically induced transparency, and with an acceptance bandwidth of δf=0.66 GHz. This memory is suitable for single photons emitted by semiconductor quantum dots. In this regime, vapor cell memories offer an excellent compromise between storage efficiency, storage time, noise level, and experimental complexity, and atomic collisions have negligible influence on the optical coherences. These results were published in Physical Review Letters 119, 060502.
We congratulate Boris Décamps for winning a poster prize at the International Conference on Laser Spectroscopy 2017. His poster was entitled Coherence Times, EPR Entanglement, and Bell Correlations in a Bose-Einstein Condensate. He reported on violation of the EPR steering criteria by spatially separated regions of a spin squeezed BEC, as well as N-particle witnesses of Bell correlations, and quantitative models of decoherence that can be used to correct for phase noise.
Congratulations to Philipp Treutlein, whom the American Physical Society recognized in the 2017 iteration of their highly selective Outstanding Referee Program. This year only 150 people of the roughly 60000 currently active referees were honored with this lifetime award. The APS instituted the program in 2008 to thank and recognize those referees, whose efforts not only keep the standards of the journals high, but also help authors improve the quality and readability of their articles.
Congratulations to Janik Wolters, who won a best poster award at the International Conference on Quantum Communication, Measurement and Computing (QCMC) in Singapore. He reported progress towards the storage of single quantum dot photons in a rubidium quantum memory. The experiments were carried out in collaboration with the Warburton group.
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. The results were reported in Science 352, 441-444 (2016).
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.