Dynamics of a stored Zeeman coherence grating in an external magnetic field

• Published in: Journal of physics. B, Atomic, molecular, and optical physics Vol. 43; no. 11; p. 115502
• Main Authors: Moretti, D, Felinto, D, Tabosa, J W R, Lezama, A
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 14.06.2010; Institute of Physics
• Subjects: Atomic and molecular physics; Atomic properties and interactions with photons; Coherence; Decay; Diffraction gratings; Evolution; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Gratings (spectra); Inhomogeneities; Lasers; Magnetic fields; Optical elements, devices, and systems; Optical storage systems, optical disks; Optics; Physics; Zeeman and stark effects; Optical storage; Light storage; Magnetic field effects; Theoretical study; Cesium; Collective process; Cold atom; Cesium Atoms; Laser beams; Zeeman effect; Optical polarization; Laser pulse; Optical phase conjugation; Time delay
• ISSN: 0953-4075; 1361-6455
• DOI: 10.1088/0953-4075/43/11/115502

We investigate the evolution of a Zeeman coherence grating induced in a cold atomic cesium sample in the presence of an external magnetic field. The gratings are created in a three-beam light storage configuration using two quasi-collinear writing and reading laser pulses with a counterpropagating pulse after a variable time delay. The phase-conjugated pulse arising from the atomic sample is monitored. Collapses and revivals of the retrieved pulse are observed for different polarizations of laser beams and for different directions of the applied magnetic field. While magnetic field inhomogeneities are responsible for the decay of the coherent atomic response, a five-fold increase in the coherence decay time, with respect to no applied magnetic field, is obtained for an appropriate choice of the direction of the applied magnetic field. A simplified theoretical model illustrates the role of the magnetic field mean and its inhomogeneity on the collective atomic response.