arXiv subjects

Pierre Meystre

Publications and source records attributed to Pierre Meystre.

43 records · Page 3Linked to original sources

arXiv2001

Spin waves in a Bose-condensed atomic spin chain

The spin dynamics of atomic Bose-Einstein condensates confined in a one-dimensional optical lattice is studied. The condensates at each lattice site behave like spin magnets that can interact with each other through both the light-induced dipole-dipole interaction and the static magnetic dipole-dipole interaction. We show how these site-to-site dipolar interactions can distort the ground state spin orientations and lead to the excitation of spin waves. The dispersion relation of the spin waves is studied and possible detection schemes are proposed.

cond-mat.soft↗

arXiv2001

Ferromagnetism in a lattice of Bose condensates

We show that an ensemble of spinor Bose-Einstein condensates confined in a one dimensional optical lattice can undergo a ferromagnetic phase transition and spontaneous magnetization arises due to the magnetic dipole-dipole interaction. This phenomenon is analogous to ferromagnetism in solid state physics, but occurs with bosons instead of fermions.

cond-mat.soft↗

arXiv2001

Phonon spectrum and dynamical stability of a quantum degenerate Bose-Fermi mixture

We calculate the phonon excitation spectrum in a zero-temperature boson-fermion mixture. We show how the sound velocity changes due to the boson-fermion interaction and we determine the dynamical stability regime of a homogeneous mixture. We identify a resonant phonon-exchange interaction between the fermions as the physical mechanism leading to the instability.

cond-mat.soft↗

arXiv2000

Atomic four-wave mixing: fermions versus bosons

We compare the efficiency of four-wave mixing in quantum degenerate gases of bosonic and fermionic atoms. It is shown that matter-wave gratings formed from either bosonic or fermionic atoms can in principle exhibit nearly identical Bragg-scattering, i.e. four-wave mixing, properties. This implies that effects such as coherent matter-wave amplification and superradiance can occur in degenerate fermi gases. While in the boson case the Bragg resonance is clearly due to `Bose enhancement', in the case of fermions the resonance is due to constructive many-particle quantum interference.

cond-mat↗

arXiv1998

Quantum Theory of Atomic Four-Wave Mixing in Bose-Einstein Condensates

We present an exact quantum mechanical analysis of collinear four-wave mixing in a multicomponent Bose-Einstein condensate consisting of sodium atoms in the F=1 ground state. Technically, this is achieved by taking advantage of the conservation laws of the system to represent its Hamiltonian in terms of angular momentum operators. We discuss explicitly the build-up of matter-wave side-modes from noise, as well as the correlations between these modes. We show the appearance of a strong quantum entanglement between hyperfine states. We also demonstrate that for finite atomic numbers, the system exhibits periodic collapses and revivals in the exchange of atoms between different spin states.

cond-mat↗

arXiv1998

Phase conjugation of trapped Bose-Einstein condensates

We consider a multicomponent atomic Bose-Einstein condensate optically trapped in a far-off resonant dipole trap. Drawing an analogy with the optical situation, we show that this system can be regarded as an matter-wave analog of optical multiwave mixing. We concentrate specifically on condenstates in the hyperfine ground state F=1, in which case a simple analogy with optical four-wave mixing can be established. This opens up the way to realize matter-wave phase conjugation, whereby an atomic beam can be ``time-reversed.'' In addition to transfering population between a "central" mode and incident and retroreflecting beams, matter-wave phase conjugation also offers novel diagnostic tools to study the coherence properties of condensates, as well as to measure the relative scattering lengths of hyperfine sublevels.

cond-mat↗

arXiv1997

Atomic detection and matter-waves coherence

We analyze several models of atomic detectors in the context of the measurement of coherence properties of matter waves. In particular, we show that an ionization scheme measures normally-ordered correlation functions of the Schrödinger field, in analogy with the optical situation. However, it exhibits a sensitivity to exchange processes that is normally absent in optics.

physics.atom-ph↗