We explore fundamental quantum physics with atoms, photons and phonons and harness it for applications in quantum metrology and quantum information. In our experiments we study many-particle entanglement in Bose-Einstein condensates and develop quantum interfaces between atoms and solid-state nanosystems such as mechanical oscillators and semiconductor quantum dots. Our research combines experiment with theory, employing techniques of laser cooling, atom chips, optomechanics, and nanofabrication. A common goal of our activities is to investigate quantum physics in systems of increasing size and complexity.
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.