Biomedical subjects

P Maddaloni

Publications and source records attributed to P Maddaloni.

5 recordsLinked to original sources

PubMed2003

Collective excitations of a trapped Bose-Einstein condensate in the presence of a 1D optical lattice.

We study low-lying collective modes of an elongated 87Rb condensate produced in a 3D magnetic harmonic trap with the addition of a 1D periodic potential which is provided by a laser standing wave along the axial direction. While the transverse breathing mode remains unperturbed, quadrupole and dipole oscillations along the optical lattice are strongly modified. Precise measurements of the collective mode frequencies at different heights of the optical barriers provide a stringent test of the theoretical model recently introduced [M. Krämer, Phys. Rev. Lett. 88, 180404 (2002)]].

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PubMed2001

Expansion of a coherent array of Bose-Einstein condensates.

We investigate the properties of a coherent array containing about 200 Bose-Einstein condensates produced in a far detuned 1D optical lattice. The density profile of the gas, imaged after releasing the trap, provides information about the coherence of the ground-state wave function. The measured atomic distribution is characterized by interference peaks. The time evolution of the peaks, their relative population, as well as the radial size of the expanding cloud are in good agreement with the predictions of theory. The 2D nature of the trapped condensates and the conditions required to observe the effects of coherence are also discussed.

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PubMed2001

Time-domain atom interferometry across the threshold for Bose-Einstein condensation.

We have performed time-domain interferometry experiments with matter waves trapped in a harmonic potential above and below the Bose-Einstein phase transition, by means of the method of separated oscillating fields, with a variable time delay T. We observe the oscillations of the population between two internal Zeeman states versus the delay T to be rapidly depleted both below and slightly above Bose-Einstein condensation. We give a quantitative explanation in terms of the phase evolution due to the entanglement between the internal and external degrees of freedom.

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PubMed2001

Josephson junction arrays with Bose-Einstein condensates.

We report on the direct observation of an oscillating atomic current in a one-dimensional array of Josephson junctions realized with an atomic Bose-Einstein condensate. The array is created by a laser standing wave, with the condensates trapped in the valleys of the periodic potential and weakly coupled by the interwell barriers. The coherence of multiple tunneling between adjacent wells is continuously probed by atomic interference. The square of the small-amplitude oscillation frequency is proportional to the microscopic tunneling rate of each condensate through the barriers and provides a direct measurement of the Josephson critical current as a function of the intermediate barrier heights. Our superfluid array may allow investigation of phenomena so far inaccessible to superconducting Josephson junctions and lays a bridge between the condensate dynamics and the physics of discrete nonlinear media.

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PubMed2000

Collective oscillations of two colliding bose-einstein condensates

Two 87Rb condensates ( F = 2, m(f) = 2, and m(f) = 1) are produced in highly displaced harmonic traps and the collective dynamical behavior is investigated. The mutual interaction between the two condensates is evidenced in the center-of-mass oscillations as a frequency shift of 6.4(3)%. Calculations based on a mean-field theory well describe the observed effects of periodical collisions both on the center-of-mass motion and on the shape oscillations.

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