Biomedical subjects

Mark G Raizen

Publications and source records attributed to Mark G Raizen.

6 recordsLinked to original sources

PubMed2004

Quantum chaos of bogoliubov waves for a bose-einstein condensate in stadium billiards.

We investigate the possibility of quantum (or wave) chaos for the Bogoliubov excitations of a Bose-Einstein condensate in billiards. Because of the mean field interaction in the condensate, the Bogoliubov excitations are very different from the single particle excitations in a noninteracting system. Nevertheless, we predict that the statistical distribution of level spacings is unchanged by mapping the non-Hermitian Bogoliubov operator to a real symmetric matrix. We numerically test our prediction by using a phase shift method for calculating the excitation energies.

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PubMed2004

Transition to instability in a kicked bose-einstein condensate.

A periodically kicked ring of a Bose-Einstein condensate is considered as a nonlinear generalization of the quantum kicked rotor. For weak interactions between atoms, periodic motion (antiresonance) becomes quasiperiodic (quantum beating) but remains stable. There exists a critical strength of interactions beyond which quasiperiodic motion becomes chaotic, resulting in an instability of the condensate manifested by exponential growth in the number of noncondensed atoms. Similar behavior is observed for dynamically localized states (essentially quasiperiodic motions), where stability remains for weak interactions but is destroyed by strong interactions.

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PubMed2003

Entanglement generation and multiparticle interferometry with neutral atoms.

We study the preparation and manipulation of states involving a small number of interacting particles. By controlling the splitting and fusing of potential wells, we show how to interconvert Mott-insulator-like and trapped BEC-like states. We also discuss the generation of "Schrödinger cat" states by splitting a microtrap and taking into practical consideration the asymmetry between the resulting wells. These schemes can be used to perform multiparticle interferometry with neutral atoms, where interference effects can be observed only when all the participating particles are measured.

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PubMed2002

Observation of cumulative spatial focusing of atoms.

We report an experimental study of the spatial distribution of ultracold cesium atoms exposed to a series of kicks from a standing wave of light. We observe cumulative focusing, leading to a spatial array of atoms which is of interest for atomic lithography. To observe the spatial distribution, we developed a free-space measurement technique that enables the reconstruction of the atomic motion as a function of time. We find increased focusing of atoms after as many as ten kicks, and the results are in good agreement with theoretical predictions.

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PubMed2002

Quantum tweezer for atoms.

We propose a quantum tweezer for extracting a desired number of neutral atoms from a reservoir. A trapped Bose-Einstein condensate is used as the reservoir, taking advantage of its coherent nature, which can guarantee a constant outcome. The tweezer is an attractive quantum dot, which may be generated by red-detuned laser light. By moving at certain speeds, the dot can extract a desired number of atoms from the condensate through Landau-Zener tunneling. The feasibility of our quantum tweezer is demonstrated through realistic and extensive model calculations.

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PubMed2002

Fluctuations and decoherence in chaos-assisted tunneling.

We study quantum dynamical tunneling between two symmetry-related islands of stability in the phase space of a classically chaotic system. The setting for these experiments is the motion of carefully prepared samples of cesium atoms in an amplitude-modulated standing wave of light. We examine the dependence of the tunneling dynamics on the system parameters and indicate how the observed features provide evidence for chaos-assisted (three-state) tunneling. We also observe the influence of a noisy perturbation of the standing-wave intensity, which destroys the tunneling oscillations, and we show that the tunneling is more sensitive to the noise for a smaller value of the effective Planck constant.

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