Events at Physics
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Events on Wednesday, December 17th, 2014
- Atomic Physics Seminar
- Application of mesoscopic atomic ensembles with random number of atoms to quantum information and quantum optics
- Time: 10:00 am
- Place: 5310 Chamberlin hall
- Speaker: Ilya Beterov, Rzhanov Institute of Semiconductor Physics :Novosibirsk State University: Novosibirsk, Russia
- Abstract: Mesoscopic ensembles of ultracold interacting atoms can be implemented by loading the cold atoms into an optical dipole trap. These ensembles are of interest for encoding of quantum information, generation of collective entangled states and observation of cooperative effects in atom-light interactions. Long-range interactions between the atoms in the ensemble lead to the effect of Rydberg blockade when not more than one atom could be excited into a Rydberg state by a narrow-band laser radiation.
The number of atoms in the trap is random and is commonly described by the Poissonian statistics. In the regime of Rydberg blockade an atomic ensemble, which consists of N atoms, can be treated as a two-level system with enhanced coupling to the laser radiation field by a factor of compared to a single atom. A single Rydberg excitation is shared between all atoms in the ensemble. Fluctuations of the frequency of Rabi oscillations between the collective states of the atomic ensembles can result in collapses and revivals of Rabi oscillations, similarly to Jaynes-Cummings model in quantum optics. These fluctuations can also lead to significant errors in quantum information processing. We have proposed to use the adiabatic passage in atomic ensembles for deterministic single-atom excitation and quantum logic gates in ensembles with unknown numbers of atoms. The double adiabatic sequences provide deterministic single-atom Rydberg excitation and remove the accumulation of undesirable dynamic phase. This can be used to implement quantum gates on collectively encoded qubits without precise knowledge of N.
- Host: Saffman