Quantop > Quantum Optics Lab > Research > Cs Cell Experiment

Below we give a short description of the project. For more information on the experiment choose one of the links in the menu-box below.

The cell experiment as it looks today at the Niels Bohr Institute

Our experiments focus on the interaction between laser light and the ground state spin of cesium atoms. We tune laser light off-resonantly to the 852nm D2 transition in cesium and couple the polarization of light to the collective total angular momentum of 10¹² cesium atoms. The atoms are contained in glass cells at room temperature, and a layer of paraffin on the inside glass walls ensures the atomic spins to have a relatively long coherence time (tens of milliseconds). We are able to couple atoms and light to each other with a sufficient strength in order to perform quantum measurements on atomic spins. The off-resonant coupling of light to atoms leads to a QND-type interaction which enables us to study quantum states generated by measurements.

Our main achievements include quantum entanglement generated by dissipation and maintained for an arbitrary long time (arXiv:1006.4344) highlighted by New Scientist (New Scientist article), quantum memory for Einstein-Podolsky-Rosen entangled states of light (Nature Physics article), entanglement assisted magnetometry with record sub-femtoTesla sensitivity (University Post article, Physics Review Letters article),  generation of entanglement between two macroscopic gas samples, demonstrating quantum memory for light and performing teleportation from light to atoms. On the road to these experiments we demonstrated quantum sensitivity of atomic spins and polarized light to the quantum fluctuations of each other. We have also developed powerful tools to characterize the atomic ground state spin. Our present work concentrates on refining the quality of entanglement and is directed towards teleportation of quantum states between atomic samples or between pulses of light and atomic samples.