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Non-classical states in mesoscopic Bose-Einstein condensates


Mesoscopic physics is concerned with the intermediate regime between microscopic single or few particle systems and macroscopic many body ensembles exhibiting collective properties. Cold atom systems are ideally suited to explore this domain as confining potentials and particle interactions can be controlled to a high degree and tuned over a wide range.

The theme of this project is the investigation of non-classical many-body quantum states. During the initial phase of the proposed experiments, such states will be realized with Bose-Einstein condensates confined in one-dimensional optical lattices. With 10 to 100 atoms per lattice site, we will vary the tunnelling rate between sites and study the crossover from a coherent to a number squeezed state, ultimately followed by the formation of a Fock, or Mott-insulator, state.

Number squeezed atomic states correspond to reduced atom shot noise and they are of particular importance in mesoscopic atomic physics, since they can lead to a spectacular improvement of the sensitivity of detectors, sensors and clocks based on matter wave interferometry. A second series of experiments aims at realizing a mesoscopic Bose-Einstein condensate in a small optical dipole trap that only supports a single bound state. This system will serve as an ideal model for various experiments regarding dynamic processes, such as condensate formation.

The subsequent efforts will focus on the coherent many-body dynamics: Starting from atoms in uncorrelated spin states, the formation of a strongly entangled many-body state ("Schrodinger cat state") in the presence of atom-atom interactions will be investigated. This correlated system will provide a novel environment to explore the role of decoherence, and to address the fundamental question of the boundary between quantum and classical physics.

Call for proposal

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