Atomic coherence

About: Atomic coherence is a research topic. Over the lifetime, 877 publications have been published within this topic receiving 29395 citations.

Evidence of Autler–Townes splitting in high-order nonlinear processes

Abstract: We demonstrate Autler–Townes (AT) splitting of four-wave mixing in an electromagnetically induced transparency window, which results from the destructive interference between a three-photon process and a five-photon process. The primary and secondary AT splittings are achieved via induced atomic coherence in a four-level Y-type atomic system. Theoretical calculations fit well with the experimentally measured results. Such controlled multichannel splitting of nonlinear optical signals can have potential applications in optical communication and quantum information processing.

Quantum Entanglement and Modulation Enhancement of Free-Electron-Bound-Electron Interaction.

Abstract: The modulation and engineering of the free-electron wave function bring new ingredients to the electron-matter interaction. We consider the dynamics of a free-electron passing by a two-level system fully quantum mechanically and study the enhancement of interaction from the modulation of the free-electron wave function. In the presence of resonant modulation of the free-electron wave function, we show that the electron energy loss and gain spectrum is greatly enhanced for a coherent initial state of the two-level system. Thus, a modulated electron can function as a probe of the atomic coherence. We further find that distantly separated two-level atoms can be entangled through interacting with the same free electron. Effects of modulation-induced enhancement can also be observed using a dilute beam of modulated electrons.

Fast light in atomic media

Abstract: Atomic media have played a major role in studies of fast light. One of their attractive features is the ability to manipulate experimental parameters to control the dispersive properties that determine the group velocity of a propagating light pulse. We give an overview of the experimental methods, based on both linear and nonlinear atom–light interaction, that have produced superluminal propagation in atomic media, and discuss some of the significant theoretical contributions to the issues of pulse preservation and reconciling faster-than-light propagation and the principle of causality. The comparison of storage of light, enhanced Kerr nonlinearity and efficient wave mixing processes in slow and fast light atomic media illustrates their common and distinct features.

Electromagnetically induced transparency and storing of a pair of pulses of light

Abstract: Electromagnetically induced transparency and light storing are discussed in the case of an atomic medium in a double $\ensuremath{\Lambda}$ configuration. A polariton description of both phenomena is systematically introduced. Analytic expressions are given which allow one to predict the shapes and phases of both the transmitted pulses and the stored and released ones as well as the atomic coherence in the storage stage. A comparison of the numerical solutions of the Maxwell-Bloch equations with the results due to the polariton model proves a strong predictive power of the latter.

Cubic-quintic condensate solitons in four-wave mixing

Abstract: We experimentally investigate the two-dimensional condensate (optical dropletlike) soliton formation and dynamics of the generated signal and probe beams in four-wave mixing (FWM) process with atomic coherence, under competition between the third- and fifth-order nonlinear susceptibilities. With such competing nonlinearities, mutual transformations among dropletlike fundamental, dipole, and azimuthally modulated vortex FWM solitons are observed. The influence of nonlinear competition on the photonic band gap is also investigated. All the results are obtained under low powers.