Quantum optics: Dedication

Abstract Electromagnetically induced transparency (EIT) is a quantum interference effect arising from different transition pathways of optical fields. Within the transparency window, both absorption and dispersion properties strongly change, which results in extensive applications such as slow light and optical storage. Due to the ultrahigh quality factors, massive production on a chip and convenient all-optical control, optical microcavities provide an ideal platform for realizing EIT. Here we review the principle and recent development of EIT in optical microcavities. We focus on the following three situations. First, for a coupled-cavity system, all-optical EIT appears when the optical modes in different cavities couple to each other. Second, in a single microcavity, all-optical EIT is created when interference happens between two optical modes. Moreover, the mechanical oscillation of the microcavity leads to optomechanically induced transparency. Then the applications of EIT effect in microcavity systems are discussed, including light delay and storage, sensing, and field enhancement. A summary is then given in the final part of the paper.

/pdf/electromagnetically-induced-transparency-in-optical-56craf0ts9.pdf

Electromagnetically induced transparency in optical microcavities

Abstract As early as 1917, Einstein had predicted that momentum is transferred in the absorption and emission of light, but it was not until the 1980's that such optical momentum transfer was used to cool and trap neutral atoms. By properly tuning laser light close to atomic transitions, atomic samples can be cooled to extremely low temperatures, the brightness of atomic beams can be enhanced to unprecedented values, and atoms can be manipulated with extraordinary precision. In this review several of the techniques for laser cooling and trapping of neutral atoms are described.

Cooling and trapping of neutral atoms

It is well known by those practicing the techniques of nonlinear optics that the power that may be generated in a frequency summing process and the gain that may be obtained in a parametric process are determined by the interaction of tire nonlinear and linear susceptibilities. In general as an atomic transition to the ground state is approached, the nonlinear susceptibility is resonantly enhanced, but at the same time the media exhibits a rapidly increasing refractive index and becomes opaque.

Nonlinear Optical Processes Using Electromagnetically Induced Transparency

We summarize recent developments in direct frequency-comb spectroscopy that allowed high-resolution, broad-bandwidth measurements of multiple atomic and molecular resonances using only a phase-stabilized femtosecond laser, opening the way for merging precision spectroscopy with coherent control.

/pdf/direct-frequency-comb-spectroscopy-1624eyk41o.pdf

Direct frequency comb spectroscopy

In the initial part of the paper, the principles of the electromagnetically induced transparency (EIT) in basic three-level schemes are sketched, and some applications of this phenomenon are described. Next a presentation follows of a five-level EIT model of Bloch equations, which was developed to reconstruct multipeak cascade-EIT spectra registered in a sample of cold 85 Rb atoms in MOT. The respective experiment is also described. The achieved good agreement between theory and performed experiment is documented and discussed.

/pdf/electromagnetically-induced-transparency-1j0ro66k7e.pdf

Electromagnetically Induced Transparency

Principles of laser cooling and trapping of atoms with regard to the magneto-optical trap (MOT) are described. Some details of the MOT and the accompanying measuring system, both constructed at the Institute of Physics, PAS in Warsaw, are given. Two examples of experimental results are shown.

/pdf/magneto-optical-trap-fundamentals-and-realization-1u8d9ixes3.pdf

Magneto-optical Trap: Fundamentals and Realization

We have investigated multiple windows of electromagnetically induced transparency (EIT) registered in a cascade scheme 5S 1/2 (F = 3) → 5P 3/2 (F′ = 3) ↔ 5D 5/2 (F″ = 4, 3, 2) of cold 85 Rb atoms in a magneto-optical trap (MOT), with a weak probe laser in the first step and with a strong coupling laser in the second step. A structure composed of up to three transparency windows is observed in the spectral profile of the probe absorption, due to a simultaneous coupling of three F″ components of a dense hfs structure of a 5D 5/2 state of the 85 Rb isotope. The experimental EIT features, as dependent on the coupling beam intensity or on the frequency detuning from the F′ = 3 ↔ F″ = 3 resonance are compared with those theoretically obtained from a five-level model. A coefficient characterizing a relative decrease of absorption at the center of the most prominent EIT peak, plotted versus the coupling beam intensity, is also presented for both the experimental and modeled spectra. A good agreement between theory and experiment is observed. As it is very simple to manipulate the positions, shapes and depths of the EIT features, the present scheme could be of interest, e.g ., for the quantum information science.

/pdf/simultaneous-coupling-of-three-hfs-components-in-a-cascade-3k9a6aiwhy.pdf

Simultaneous coupling of three hfs components in a cascade scheme of EIT in cold 85Rb atoms

The possible use of the nonlinear Faraday effect for optical limitation of the laser power is investigated in a resonant Faraday medium placed between two crossed polarizers. The results are comparable with those obtained at strong magnetic fields as a result of the linear Faraday effect. Advantages of the method are the narrow bandwidth and the wide field of view. The investigations are interesting from the viewpoint of applications for optical sensor protection and automation of the experiment. All measurements are performed at the Fg = 2 → Fe = 1 hyperfine structure transition of the 87Rb D1 line.

/pdf/nonlinear-faraday-rotation-for-optical-limitation-e3hp3yqkel.pdf

Nonlinear Faraday rotation for optical limitation

A diode laser system for spectroscopy of cold Rb atoms is reported. The apparatus is mainly aimed at studying the electromagnetically induced transparency (EIT) in cold environment. The system is based on a rubidium magneto-optical trap (MOT). Two additional extended cavity diode lasers provide the light beams for experimenting, e.g., a coupling- and probe- beam for EIT. The set-up is equipped with channels for detection of absorption and fluorescence. Some system elements of the ones made in our laboratory, in particular, the electronic system for data acquisition and for control of MOT and experiment, are presented in some detail. Records of probe beam absorption spectra of cold Rb, exhibiting profiles due to EIT in multilevel cascade scheme, registered by the use of this apparatus, are presented as an example of the setup performance.

M. Głódź

Papers

Electromagnetically Induced Transparency

Magneto-optical Trap: Fundamentals and Realization

Simultaneous coupling of three hfs components in a cascade scheme of EIT in cold 85Rb atoms

Nonlinear Faraday rotation for optical limitation

Laser system for EIT spectroscopy of cold Rb atoms