New Mechanism for the Production of Optical Resonances with Subnatural Linewidths (original) (raw)

Controlled polarization rotation of an optical field in multi-Zeeman-sublevel atoms

Physical Review A, 2006

We investigate, both theoretically and experimentally, the phenomenon of polarization rotation of a weak, linearly-polarized optical (probe) field in an atomic system with multiple three-level electromagnetically induced transparency (EIT) sub-systems. The polarization rotation angle can be controlled by a circularly-polarized coupling beam, which breaks the symmetry in number of EIT subsystems seen by the left- and right-circularly-polarized components of the weak probe beam. A large polarization rotation angle (up to 45 degrees) has been achieved with a coupling beam power of only 15 mW. Detailed theoretical analyses including different transition probabilities in different transitions and Doppler-broadening are presented and the results are in good agreements with the experimentally measured results.

Competition between the tensor light shift and nonlinear Zeeman effect

Many precision measurements (e.g., in spectroscopy, atomic clocks, quantum-information processing, etc.) suffer from systematic errors introduced by the light shift. In our experimental configuration, however, the tensor light shift plays a positive role enabling the observation of spectral features otherwise masked by the cancellation of the transition amplitudes and creating resonances at a frequency unperturbed either by laser power or beam inhomogeneity. These phenomena occur thanks to the special relation between the nonlinear Zeeman and light shift effects. The interplay between these two perturbations is systematically studied and the cancellation of the nonlinear Zeeman effect by the tensor light shift is demonstrated.

Electromagnetically induced absorption and transparency due to long-lived Zeeman coherence

2009

The rapidly developing field of quantum communication has emerged from the fusion of different branches of physics and computer science. It promises very fast, reliable and secure data transmission between distant sites. The practical implementation of quantum networks will more likely be realized using solid state technology; however, resonant atomic media can provide an ideal testing ground for quickly exploring different ideas before developing expensive and time-consuming technologies. It is well known that quantum interference effects in resonant atomic media can dramatically change the absorption and dispersion of light propagating in an atomic sample. This forms the basis of a wealth of interesting and sometimes counterintuitive phenomena, which have the demonstrated potentials for storage and retrieval of information carried by light. In this chapter we discuss the two complementary effects of electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) due to long-lived Zeeman coherences in atomic media. Both effects result in very narrow absorption profile resonances and steep sign-reversible dispersion. We show that in addition to ground-level coherence, coherent population oscillations between the ground and excited levels contribute to resonances with sub-natural width. We present a study of the optical properties of coherently prepared atomic media paying particular attention to steep sign-reversible dispersion and enhanced Kerr nonlinearity, which are crucial to such phenomena as few-photon nonlinearity, slow and fast light, and storage and revival of light pulses.

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

Journal of Physics B: Atomic, Molecular and Optical Physics, 2010

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 laser pulses and reading 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 the 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 fivefold 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.

Measurement of the Zeeman-like ac Stark shift

Physical Review A, 2001

We demonstrate that when laser light is circularly polarized and properly detuned, the ac Stark shift of an alkali-metal atom in its ground state takes the form of a pure Zeeman shift. The condition is satisfied when the laser frequency is between the D 1 and D 2 transition ...