As stated in the text, Figs. 3 and 4 (transmission versus probe laser detuning) were taken at an energy of 10 nJ in a 0.5-mm-diam beam. We should have noted that when the probe energy is increased to 150 n3 (— 10" W/cm ) the absorption cross section at the transmission maximum increases by a factor of approximately 2. At this energy density, with or without the coupling laser present, transmitted probe energy is no longer linear with incident probe energy.

Observation of Electromagnetically Induced Transparency in Collisionally Broadened Lead Vapor

Quantum light–matter interfaces are at the heart of photonic quantum technologies. Quantum memories for photons, where non-classical states of photons are mapped onto stationary matter states and preserved for subsequent retrieval, are technical realizations enabled by exquisite control over interactions between light and matter. The ability of quantum memories to synchronize probabilistic events makes them a key component in quantum repeaters and quantum computation based on linear optics. This critical feature has motivated many groups to dedicate theoretical and experimental research to develop quantum memory devices. In recent years, exciting new applications, and more advanced developments of quantum memories, have proliferated. In this review, we outline some of the emerging applications of quantum memories in optical signal processing, quantum computation and non-linear optics. We review recent experimental and theoretical developments, and their impacts on more advanced photonic quantum technologies based on quantum memories.

https://tandfonline.com/doi/pdf/10.1080/09500340.2016.1148212

Quantum memories: emerging applications and recent advances.

Preface 1. Planck's radiation law and the Einstein coefficients 2. Quantum mechanics of the atom-radiation interaction 3. Classical theory of optical fluctuations and coherence 4. Quantization of the radiation field 5. Single-mode quantum optics 6. Multimode and continuous-mode quantum optics 7. Optical generation, attenuation and amplification 8. Resonance fluorescence and light scattering 9. Nonlinear quantum optics Index

The quantum theory of light.

Cavity optomechanical systems have been shown to exhibit an analogon to atomic electromagnetically induced transparency that a transmission window for the propagation of the probe field is induced by a strong control field when the resonance condition is met. Sharp transmission features controlled by the control laser beam enable many applications ranging from force sensors to quantum communication. In recent years, there has been significant progress in both theoretical and experimental studies of this phenomenon, driven by the development of nanophotonics as well as the improvement of nano-fabrication techniques. Optomechanically induced transparency has been found to manifest in numerous different physical mechanisms, e.g., nonlinear optomechanically induced transparency, double optomechanically induced transparency, parity-time symmetric optomechanically induced transparency, and optomechanically induced transparency in various hybrid optomechanical systems, etc. These results offer a pathway towards an integrated quantum optomechanical memory, show the utility of these chip-scale optomechanical systems for optical buffering, amplification, and filtering of microwave-over-optical signals, and may be applicable to modern optical networks and future quantum networks. Here, we systematically review the latest research progress on the fundamentals and applications of optomechanically induced transparency. Perspectives and opportunities on future developments are also provided by focusing on several promising topics.

Fundamentals and applications of optomechanically induced transparency

We present a theoretical and experimental study of the ultra-narrow bandwidth Faraday anomalous dispersion optical filter (FADOF) operating at the rubidium D1 line (795 nm). This atomic line gives better performance than other lines for the main FADOF figures of merit, e.g. simultaneously 71% transmission, 445 MHz bandwidth and 1.2 GHz equivalent noise bandwidth.

Ultra-Narrow Faraday Rotation Filter at the Rb D1 Line

We report experimental observations on the simultaneous electromagnetically induced transparency (EIT) effects for probe and trigger fields (double EIT) as well as the enhanced cross-phase modulation (XPM) between the two fields in a four-level tripod EIT system of the D1 line of 87Rb atoms. The XPM coefficients (larger than 2 x 10(-5) cm2/W) and the accompanying transmissions (higher than 60%) are measured at a slight detuning of the probe field from the exact EIT-resonance condition. The system and enhanced cross-Kerr nonlinearities presented here can be applied to quantum information processes.

Enhanced Cross-Phase Modulation Based on a Double Electromagnetically Induced Transparency in a Four-Level Tripod Atomic System

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) subsystems. 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\ifmmode^\circ\else\textdegree\fi{}) has been achieved with a coupling beam power of only $15\phantom{\rule{0.3em}{0ex}}\mathrm{mW}$. 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.

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

We investigate, both theoretically and experimentally, the cross-Kerr nonlinearity generated in a four-level tripod system in the 87Rb D1 line. The system exhibits simultaneous electromagnetically induced transparency (EIT) windows for two weak (probe and trigger) fields and the enhanced cross-Kerr nonlinearity by EIT. The cross-Kerr nonlinear phase shifts for probe (trigger) field are measured at several different intensities of trigger (probe) field. The results show that large cross-phase modulation (XPM) coefficients can be achieved at low light intensities.

Enhanced cross-Kerr nonlinearity via electromagnetically induced transparency in a four-level tripod atomic system

We present the experimental observations and theoretical calculations of two electromagnetically induced transparency (EIT) windows and an enhanced EIT signal in a four-level tripod system of D1 line of 87Rb atoms. The two EIT dips produced by a strong coupling beam and a weak trigger beam were observed in the absorption spectrum of probe field, when the frequency detuning of the trigger beam was different from that of the coupling beam. When the frequency detuning of the trigger beam was near or equal to that of the coupling beam, the total depth of the EIT dip created by the coupling beam clearly became larger. The experimental measurements were in agreement with theoretical calculations.

http://iopscience.iop.org/article/10.1088/0953-4075/40/16/002/pdf

Two electromagnetically induced transparency windows and an enhanced electromagnetically induced transparency signal in a four-level tripod atomic system

We present our experimental and theoretical studies of multi-dark-state resonances (MDSRs) generated in a unique cold rubidium atomic system with only one coupling laser beam. Such MDSRs are caused by different transition strengths of the strong coupling beam connecting different Zeeman sublevels. Controlling the transparency windows in such an electromagnetically induced transparency system can have potential applications in multiwavelength optical communication and quantum information processing.

Xudong Yang

Papers

Enhanced Cross-Phase Modulation Based on a Double Electromagnetically Induced Transparency in a Four-Level Tripod Atomic System

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

Enhanced cross-Kerr nonlinearity via electromagnetically induced transparency in a four-level tripod atomic system

Two electromagnetically induced transparency windows and an enhanced electromagnetically induced transparency signal in a four-level tripod atomic system

Multi-dark-state resonances in cold multi-Zeeman-sublevel atoms.