Distinguishing coherent atomic processes using wave mixing

We are able to clearly distinguish the processes responsible for enhanced low-intensity atomic Kerr nonlinearity, namely coherent population trapping and coherent population oscillations in experiments performed on the Rb D1 line, where one or the other process dominates under appropriate conditions. The potential of this new approach based on wave mixing for probing coherent atomic media is discussed. It allows the new spectral components to be detected with sub-kHz resolution, which is well below the laser linewidth limit. Spatial selectivity and enhanced sensitivity make this method useful for testing dilute cold atomic samples.Comment: 9 pages, 5 figure

Electromagnetically Induced Transparency versus Nonlinear Faraday Effect. Coherent Control of the Light Beam Polarization

We report on experimental and theoretical study of the nonlinear Faraday effect under conditions of electromagnetically induced transparency at the 5$S_{1/2} \to 5P_{3/2} \to 5D_{5/2}$ two-photon transition in rubidium vapors. These transitions realize the inverted Y model which combines the $\Lambda$ and ladder systems. Strong nonlinearity allowing for large rotation angles of a probe beam tuned to the $S\to P$ transition was obtained by creation of quantum superpositions of magnetic sublevels (Zeeman coherences) in the rubidium ground state ($\Lambda$ scheme). Additionally, electromagnetically induced transparency was accomplished in a ladder scheme by acting with an additional strong coupling laser on the $P\to D$ transition. Under conditions of a two-photon resonance the rotation was significantly reduced, which is interpreted as a competition between the two processes. The effect was observed in sub-Gauss magnetic fields and could be used for efficient coherent control of generation of the ground-state coherences, e.g. for controlling the polarization state of the probe light.Comment: 7 pages, 12 figures, submitted to Phys. Rev.

Doppler-free nonlinear faraday rotatior spectroscopy of rb atoms

The aim of this book is to present new results in rapidly developing fields of nonlinear optics such as atomic coherence, magneto-optics of atomic media, Doppler-free spectroscopy, time-domain spectroscopy of dense atomic vapors, frequency comb spectroscopy and atom-surface interactions. The discovery of such coherent effects as coherent population trapping (CPT), electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) opened a new avenue for development in many fields of nonlinear optics. Investigations during the last decade have shown many related new results and approaches in nonlinear optics. These include nonlinear magneto-optical processes (NMOP) in the context of high precision magnetometry, quantum information storage and processing, magnetic resonance imaging and magnetic particle detection; the use of ultra-thin (nanometric length) atomic vapor cells in magneto-optical experiments, which show new peculiarities of both coherent effects and NMOP; the use of frequency and amplitude modulated laser beams for NMOP studies in atomic vapors with the aim of extending the range of ultra-precise magnetometers to stronger, particularly geomagnetic fields; application of the counter-propagating beam technique to reveal the Doppler free nonlinear Faraday rotation signals, as a spectroscopic tool and for applications; enhanced nonlinearity due to atomic coherence in multi-state systems; experimental study of EIT in solids; the use of the phase stabilized frequency domain combs of femtosecond laser pulses for velocity selective optical pumping of atomic hyperfine levels, as a direct frequency comb spectroscopy; time-domain nonlinear spectroscopy of dense atomic vapors; atom-surface interactions and laser induced adsorption and desorption of alkali atoms on the surface of solid materials for nanotechnology application

Quantum coherence in the rubidium 5S-5P-5D ladder system : applications in frequency conversion, imaging, and squeezing

The rubidium three-level ladder system consisting of the 5S, 5P and 5D states provides a readily accessible and powerful tool for extreme non-linear optics. We consider some phenomena and applications based on this system, including efficient frequency upconversion,state-selective cold atom imaging, and quantum squeezing

Forty years after the first dark resonance experiment: an overview of the COSMA project results

Coherent Optics Sensors for Medical Applications (COSMA) was a European Marie Curie Project running from 2012 to 2016, with the participation of 10 teams from Armenia, Bulgaria, India, Israel, Italy, Poland, Russia, UK and USA. The main objective was to focus theoretical and experimental research on biomagnetic phenomena, with the specific aim to develop all-optical sensors dedicated to their detection and suitable for applications in clinical diagnostics. The paper presents some of the most recent non–technical results obtained during the exchange visits of the involved scientists, after an introduction about the phenomenon which is the pillar of this kind of research and of many other new fields in laser spectroscopy, atomic physics and quantum optics