Quantum Optics Seminar by Dr. Andrew Hilliard – Niels Bohr Institute - University of Copenhagen

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Niels Bohr Institute > Calendar > 2011 > Quantum Optics Seminar...

Quantum Optics Seminar by Dr. Andrew Hilliard

Neutral atoms stored in optical traps provide a versatile platform for fundamentalstudies of quantum mechanics at the single event level and have potential forapplication in quantum information processing. Far off-resonance optical trapsprovide conservative potentials and excellent isolation from the environment, andthey may be arranged to produce arbitrary arrays of traps, where each trap is occupiedby a single, individually addressable atom. A major challenge associated with thisapproach is the reliable generation of single atom occupancy in each trap. In this talk,I report a loading efficiency of 82.7% in an optical microtrap. This is achieved bymanipulating the collisions between pairs of trapped atoms through tailored opticalfields and directly observing the resulting single atoms in the trap. I will also describethe fluorescence imaging technique with which we can count up to several atoms inthe microtrap. This technique uses a standing wave of laser light that is blue detunedfrom resonance for an atom at the centre of the microtrap. The blue detuning limitstrap-loss from inelastic light-assisted collisions and the optical standing wave inducesa spatial modulation of the imaging beam intensity, leading to a form of Sisyphuscooling. Unlike other forms of blue detuned laser cooling, this mechanism does notpump the atom(s) into optically dark states, making it suitable for fluorescence

imaging.