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Coherence effects in three- and four-level laser-cooled rubidium systems
This thesis presents developmental work on the existing magneto-optical trap (MOT) system and novel studies of coherence effects. The developmental work was carried out on the experimental apparatus used previously in this laboratory in order to perform experiments to study coherence effects in three- and four-level rubidium systems in the MOT. This developmental work includes the upgrading and installation of new laser systems, the improvement of the MOT, the installation of data acquisition hardware and software, and the commissioning of a new “second generation” MOT. As part of our studies of coherence effects, we present a wide-ranging theoretical and experimental study of non-adiabatic transient phenomena in a A system which exhibits electromagnetically induced transparency when a strong coupling field is rapidly switched on or off using a Pockels cell. The theoretical treatment uses a Laplace transform approach as well as standard numerical methods to solve the time-dependent density matrix equation. The results show clear Rabi oscillations and transient gain without population inversion of a weak probe in parameter regions not previously studied, and provide insight into the transition dynamics between bare states and dressed states. Experimental studies of a doubly driven V system are also reported, together with a theoretical dressed-state analysis of such systems. The expected three-peak spectrum is explored for various coupling field strengths and detunings. In all this work we have found good agreement between the theory and the experimental spectra once light shifts and uncoupled absorption in the rubidium system are taken into account
Polarization-based Light-Atom Quantum Interface with an All-optical Trap
We describe the implementation of a system for studying light-matter
interactions using an ensemble of cold rubidium 87 atoms, trapped in a
single-beam optical dipole trap. In this configuration the elongated shape of
the atomic cloud increases the strength of the collective light-atom coupling.
Trapping all-optically allows for long storage times in a low decoherence
environment. We are able to perform several thousands of measurements on one
atomic ensemble with little destruction. We report results on paramagnetic
Faraday rotations from a macroscopically polarized atomic ensemble. Our results
confirm that strong light-atom coupling is achievable in this system which
makes it attractive for single-pass quantum information protocols.Comment: 8 pages, 4 figure
Prospects for photon blockade in four level systems in the N configuration with more than one atom
We show that for appropriate choices of parameters it is possible to achieve
photon blockade in idealised one, two and three atom systems. We also include
realistic parameter ranges for rubidium as the atomic species. Our results
circumvent the doubts cast by recent discussion in the literature (Grangier et
al Phys. Rev Lett. 81, 2833 (1998), Imamoglu et al Phys. Rev. Lett. 81, 2836
(1998)) on the possibility of photon blockade in multi-atom systems.Comment: 8 page, revtex, 7 figures, gif. Submitted to Journal of Optics B:
Quantum and Semiclassical Optic