This talk is divided into two parts: in the first part I will present our experimental set-up in Nottingham towards the realisation of mixtures of cold molecules, and in the second part I will show our recent theoretical results on genuine tripartite entanglement in Bose-Einstein condensates.
Polar Molecules
The research field of ultra-cold molecules has grown in the last decade bringing many researchers to investigate the unique properties of these fascinating systems. Their additional internal degrees of freedom compared to the atoms, make ultra-cold molecules suitable candidates for the study of new physical phenomena with an impact on a large variety of fields, including atomic, molecular and optical physics, chemistry, quantum information science and quantum simulations, condensed matter physics and cosmology. Our goal is to realise lithium-caesium mixtures, which are especially interesting with respect to studying stationary and mobile impurities, transport measurements and exotic phases in optical lattices. I will present details of our optical and vacuum set-up, and discuss the state of the art of our experiment. I will furthermore present a proposal for a scheme to create and manipulate cold polar molecules close to the surface of an atom chip. I will give details of the required magnetic field to ramp the molecules over the Feshbach resonance and show that it is possible to polarise them by apply a potential between the chip surface and a copper ring placed below it.
Quantum Correlations
We investigate the genuine multipartite nonlocality of three-mode Gaussian states of continuous variable systems. For pure states, we present a simplified procedure to obtain the maximum violation of the Svetlichny inequality based on displaced parity measurements, and we analyze its interplay with genuine tripartite entanglement measured via Rényi-2 entropy. The maximum Svetlichny violation admits tight upper and lower bounds at fixed tripartite entanglement. As an example, we study a system represented by a Bose-Einstein condensate interacting with a ring cavity field in the presence of a strong off-resonant pumping laser. The state of this system can be described by a three-mode Gaussian state, where two are the atomic modes corresponding to atoms populating upper and lower momentum sidebands and the third mode describes the scattered cavity field light. We show that, as a consequence of the collective atomic recoil lasing mechanism, the state of the system exhibits genuine tripartite entanglement and nonlocality, which can be revealed by a robust violation of the Svetlichny inequality when performing displaced parity measurements.
