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Summary form only given. The modern development of quantum optics began with the realization that the coherence properties and most of the statistical properties of light are determined by a succession of correlation functions for the quantized electromagnetic field. Many of the cold-atom experiments of the past decade that are part of the foundation of the new field of atom optics have close optical...
Summary form only given. Bosonic stimulation as the principal mechanism for the growth of a Bose-Einstein condensate was first introduced and quantitatively evaluated by Gardiner et al., and this was subsequently experimentally verified by Miesner et al. Although agreement between experiment and theory is not perfect, it is clear that the predicted mechanism of stimulated emission into the condensate...
Summary form only given. Since the invention of the laser, the field of photonics has progressed through the development of engineered materials which mold the flow of light. Photonic band gap (PBG) materials are a new class of dielectrics which facilitate the micromanipulation of photons in much the same way that the semiconductor manipulates the flow of electrons. A PBG material exhibits a complete...
Summary form only given. Nonlinear collective and interacting spin models have long endured as tractable, nonlinear quantum models with wide ranging relevance. Such models have appeared in nuclear physics, laser physics, condensed matter physics and of course as a theoretical laboratory to investigate aspects of nonlinear field theories. In many cases however the match between model and experiment...
Summary form only given. One of the key elements of quantum communication is the generation of maximally entangled states between distant nodes of a quantum network. We present an entanglement purification scheme which generates maximally entangled states in finite Hilbert spaces from the continuous two-mode squeezed states. With high probabilities, we get a more entangled stale, and the entanglement...
Summary form only given. Recently, atom manipulation by using optical near fields has been attracting a lot of interests. Optical near field can be localized in a nanometric region, being free from the diffraction limit in contrast to propagation light. The intensity distribution of optical near field decays rapidly as an exponential-like function. Because such a spatially inhomogeneous light field...
Summary form only given. Correlated and entangled single photon states have made possible many fundamental studies in quantum optics such as the Bell-type test of hidden variables and non-locality, explorations of quantum interference properties, and investigations of quantum information processing and quantum communications technologies such as quantum cryptography, quantum computing, and quantum...
Summary form only given. Optical parametric amplifiers (OPA) have been demonstrated previously as a system capable of generating strongly squeezed states. The output from these systems is typically a "vacuum squeezed state" where the beam has no coherent amplitude. Such squeezed states may be used to improve the performance of optical measurements limited by quantum noise, or as reported,...
Summary form only given. We report the observation of an interesting coherent effect, which looks very much like the so-called Zeeman coherence in atomic physics and is indeed an optically induced entanglement between two oppositely oriented electrons confined to one single QD. This is the first observation of entanglement in semiconductors and is an important step in realizing a quantum logic device...
Summary form only given. The transition between quantum and classical systems is usually ascribed to decoherence effects, which become increasingly important for larger size systems and tend to obscure the quantum behavior. Decoherence effects also come into play in the famous thought 'Gedanken' experiments on the wave-particle duality of matter. For example, in a double slit experiment with electrons,...
Summary form only given. Complementarity is one of the most basic principles of quantum mechanics. A quantum mechanical object, be it a photon or a massive particle, shows position (particle-like) or momentum (wave-like) attributes exclusively depending on the experimental situation. Over the years, Young's two-slit experiment has been emphasized as a good example of complementarity. We report two...
Summary form only given. Design and excitation of novel quantum states and the measurement of those states is driven by both fundamental and technological goals. For example, the study of Schrodinger cat states touches upon the basic measurement hypotheses of quantum mechanics while the establishment of particular coherent superposition states is the starting point for the process of coherent control...
Summary form only given. A single-mode quantum-phase operator cannot be simultaneously Hermitian and work in an unrestricted Hilbert-space, recently, work on finding the operator corresponding to the relative phase between two harmonic oscillators has been undertaken. In particular we suggested an experimental implementation of a generalization of the relative-phase operator derived by Luis and Sanchez-Soto...
Summary form only given. Using the density matrix formulation of quantum mechanics, the optically-heterodyne-detected coherent Raman scattering signal in the out-of-phase configuration, under the off-resonant condition, is given.
Summary form only given. Recent experimental studies have revealed distinct characteristics of optical near fields. Highly localized optical near fields could be applied to not only a high-resolution microscope beyond the diffraction limit of light but also fabrication of nanometric devices. From this point of view, a theory, which quantitatively deals with interactions between a nanometric probe...
Summary form only given. The preparation of quantum systems in pure states is a prerequisite for coherent control. In this context laser cooling of trapped particles to the ground state of the confining potential is a powerful tool for preparing e.g. ions for quantum logic. In particular sideband cooling has been demonstrated to be the most efficient technique, allowing to achieve more than 99% of...
Summary form only given. Electromagnetically induced focussing (EIF) results in the control of lensing action on one light field by the application of another. This has been shown to occur in three level cascade systems. We consider an extension to four level cascade schemes where the upper transition is coupled by a RF field. Previous work on EIT in a four level cascade manifold has shown that the...
Summary form only given. We show that, even in a far-off-resonance Raman system driven by a strong coupling field, the combination of a high density and a small coherence decay results in a steep dispersion in the vicinity of two-photon resonance and, consequently, allows us to slow down the speed of light pulses and to produce an efficient nonlinear conversion. We show analytically that the interaction...
Summary form only given. It is well-known that nonlinear interference effects in the resonant atom-light interaction can lead to interesting and important phenomena, such as electromagnetically induced transparency (EIT) of atomic medium, coherent population trapping, lasing without inversion, and others. Common to all these phenomena is the appearance of light-induced coherence between atomic levels,...
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