Dispersión de nubes atómicas frías por haces de

luz estructurada

R. JáureguiInstituto de FísicaUNAMrocio@fisica.unam.mx

Temixco, septiembre 2012

Scattering of dilute thermal atomic clouds by structured beams

• Experimental and theoretical results for the scattering effects on free falling dilute thermal atomic clouds that traverse a microscopically structured laser beam with parabolic symmetry.

• The dynamics of the phase space distribution is studied. • As previously proposed, the atomic clouds were

observed to split into two or more clouds with a well defined distribution of velocities.

• It is shown that the product of the angular momentum along the axis of main propagation of the laser beam with the linear momentum along one of the directions perpendicular to that axis is directly transmitted from the light beam to the atomic cloud.

General framework

• Predesigned structured light playing the role for cold matter that crystals or material cavities play for light.

• Structured photons?

• Transfer of dynamical variables from light to matter

Structured light beams

• Plane waves always useful (Fourier transform)

• Structure of a beam:

F(k)

Polarization

• Propagation invariant beams

Weber modes

• Propagation invariant modes with parabolic cylinder symmetry

Weber Modes

Weber Modes

• Propagation invariant

• Fourier decomposition in a cone

• Unusual gradients of the intensity • Dynamical variable

Lz Py

Weber modes

Weber modes

Weber modes

Cold Atoms

• Atom cooling

• Atom trapping

• Thermal atoms versus degenerate gases

Atom Trapping

Degenerate gases

Trapping-cooling system

J. Fortagh group, Univ. Tuebingen

Absorption Imaging

Atom-light interaction

Experimental set-up

670 x420m.

Results:

Results: Experiments vs Theory

Results: Experiments vs Theory

Evolution in phase space

Evolution LzPy

Theory vs experiment

Conclusions

• Weber beams as thermal cloud splitters

• Direct numerical simmulation with no free parameters.

• Observation of transfer of a different dynamical dynamical variable from light to matter.

Scope

• BEC:

Experimental results

Simulation

BEC

• Four quantum fluids• Two Gross-Pitaevskii• Two Bose distributions• Interaction ground-ground, ground-excited,excited-excited• Accurate description initial state• Evolution: classical fluid, relevance

quantum pressure

Some advances

Preliminary theoretical results

Carlos Luis Hernández

Pedro Antonio Quinto

Rocio Jáuregui

Simon BernonHelge HattermannJószef Fortagh