arXiv subjects

F. Gerbier

Publications and source records attributed to F. Gerbier.

25 records · Page 2Linked to original sources

arXiv2003

Momentum Spectroscopy of Phase Fluctuations of an Elongated Bose-Einstein Condensate

We have measured the momentum distribution of an elongated BEC (aspect ratio of 152), for temperatures below the critical temperature. The corresponding coherence length is significantly smaller than the condensate length in a wide range of temperature, in quantitative agreement with theoretical predictions. The Lorentzian shape of the momentum spectrum supports the image of a phase fluctuating quasicondensate.

cond-mat.stat-mech↗

arXiv2003

One-dimensional behavior of elongated Bose-Einstein condensates

We study the properties of elongated Bose-Einstein condensates. First, we show that the dimensions of the condensate after expansion differs from the 3D Thomas-Fermi regime. We also study the coherence length of such elongated condensates.

cond-mat↗

arXiv2003

Momentum distribution and correlation function of quasicondensates in elongated traps

We calculate the spatial correlation function and momentum distribution of a phase-fluctuating, elongated three-dimensional condensate, in a trap and in free expansion. We take the inhomogeneous density profile into account {\it{via}} a local density approximation. We find an almost Lorentzian momentum distribution, in stark contrast with a Heisenberg-limited Thomas-Fermi condensate.

cond-mat↗

arXiv2003

Momentum spectroscopy of 1D phase fluctuations in Bose-Einstein condensates

We measure the axial momentum distribution of Bose-Einstein condensates with an aspect ratio of 152 using Bragg spectroscopy. We observe the Lorentzian momentum distribution characteristic of one-dimensional phase fluctuations. The temperature dependence of the width of this distribution provides a quantitative test of quasi-condensate theory. In addition, we observe a condensate length consistent with the absence of density fluctuations, even when phase fluctuations are large.

cond-mat.soft↗

arXiv2002

Phase coherence length of a Bose-Einstein condensate

We report on the measurement of the momentum distribution of an elongated Bose-Einstein condensate. A broadening of the distribution with increasing temperature is observed, which is clear evidence for phase fluctuations in the sample.

cond-mat↗

arXiv2001

Atom laser divergence

We measure the angular divergence of a quasi-continuous, rf-outcoupled, free-falling atom laser as a function of the outcoupling frequency. The data is compared to a Gaussian-beam model of laser propagation that generalizes the standard formalism of photonic lasers. Our treatment includes diffraction, magnetic lensing, and interaction between the atom laser and the condensate. We find that the dominant source of divergence is the condensate-laser interaction.

cond-mat↗

arXiv2001

Quasi-continuous atom laser in the presence of gravity

We analyse the extraction of a coherent atomic beam from a trapped Bose-Einstein condensate using a rf transition to a non-trapping state at T=0 K. Our quantum treatment fully takes gravity into account but neglects all interactions in the free falling beam. We obtain an analytical expression of the output rate and of the wave function of the extracted beam, i.e. the output mode of the ``atom laser''. Our model reproduces satisfactorily experimental data without any adjustable parameter.

physics.atom-ph↗