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Summary form only given. We present a novel method for the characterization of quantization energy fluctuations in single semiconductor quantum wires (QWRs). The method takes advantage of a recently developed femtosecond near-field scanning optical microscope (NSOM). We demonstrate that the shape of degenerate near-field pump-probe traces sensitively depends on the detuning between the laser photon...
Summary form only given. We have experimentally demonstrated that the two-photon probability amplitudes of photon pairs generated using spontaneous parametric down conversion from separate nonlinear crystals, under the conditions outlined above, remain independent and cannot be used to engineer more complex quantum states. The spontaneous nature of the down-conversion process prevents pairs of photons...
Summary form only given. A type-II phase-marched parametric downconverter can be used to produce polarization-entangled photon pairs. We propose a production scheme for polarization-entangled photon pairs by using a pair of optical parametric amplifiers (OPAs) whose narrowband generation rate is high enough to make it a practical source for a trapped-atom quantum memory. For a type-II system using...
Summary form only given. Progress in cw optical parametric oscillators (OPOs) has been spurred by improvements and new developments in several areas during the last years: novel LiNbO/sub 3/ periodically poled (PP) crystals, powerful single-frequency pump sources, durable and broad-band dielectric coatings, frequency stabilization techniques, and novel device configurations.
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. Resonant optics at a gas-solid interface can exhibit unprecedented sensitivity to gas-surface interactions if one restricts the gas volume that determines the optical response to very small distances to the surface. In the case of evanescent wave or surface plasmon spectroscopy the excited gas volume is limited by the depth of the wave penetration into the gas. Due to this...
Summary form only given. Recently, modulational instability (MI) in periodic structures has attracted considerable attention. We study MI in a bulk nonlinear medium with a Bragg grating along the direction of propagation. In these structures, MI is caused by mutual interplay among dispersion, diffraction and nonlinear effects and results in spatial and temporal effects simultaneously. Light propagation...
Summary form only given. Passive optical limiters are used to protect human eyes or sensitive optical elements from laser damage. Excited-state absorption (ESA) evoked transitions from one excited state to a higher one is a prerequisite for efficient optical limiting. Numerous parameters of the system as well as laser pulse characteristics make it difficult to determine optimum conditions for efficient...
Summary form only given. Time-integrated (TI) and time-resolved (TR) four-wave-mixing (FWM) techniques have been employed successfully to study the relaxation dynamics of coherent excited states in semiconductors and semiconductor quantum wells. A large number of experimental and theoretical studies on FWM have been mainly focused on the resonant FWM signals in thin semiconductors with thicknesses...
Summary form only given. Recent development of micro-photoluminescence (/spl mu/-PL) spectroscopy has enabled us to observe photoluminescence from a single quantum dot, which has sharp homogeneous linewidth and long coherence time. We report on the /spl mu/-PL spectra of single GaAs/AlGaAs quantum dots grown on a (411)A surface of a GaAs substrate. We have observed sharp luminescence lines originating...
Summary form only given. Incoherent emission (fluorescence and Raman scattering) of an ensemble of randomly oriented molecules is isotropic. However, when these molecules are homogeneously embedded in a sample shape (such as spheres, spheroids, cylinders, ...) which concentrates the internal intensity distribution, the resulting fluorescence emission can become anisotropic. Based on reciprocity principle,...
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,...
Summary form only given. Application of an ion trap as a frequency standard requires cooling of the ions or an accurate knowledge of the ion motion to compensate for frequency shifts due to the second-order Doppler effect. In this contribution we report on the observation of atomic coherence effects, which originate from the characteristic motion of Paul. Trapped ions and how these effects can be...
Summary form only given. The strong coupling between an atom and the light field in an optical microresonator causes a single atom to alter the transmission of the cavity significantly, allowing its continuous observation. At the same time, the strong coupling leads to novel optical forces acting on the atom. It was predicted that it should be possible to trap an atom with single intracavity photons.
Summary form only given. We report on recent experiments to use dark line coherent population trapping (CPT) resonances in cesium vapor as the basis for a compact frequency reference. The resonance is excited by directly modulating the injection current of a VCSEL at one-half the ground state hyperfine transition of Cs (4.6 GHz) to produce RF sidebands on the optical carrier. The laser output is then...
Summary form only given. We report results from an efficient new method for producing translationally cold (T<1 mK) potassium molecules in the ground X/sup 1//spl Sigma//sub g//sup +/ electronic state. We use the two-photon "R-transfer" scheme conceptually similar to a proposal by Band and Julienne (1995). First, ultracold potassium atoms in a MOT are photoassociated at long range to...
Summary form only given. Since the first observations of Bose Einstein condensates (BEC) in dilute atomic gases, there has been considerable interest in observing effects in atomic BEC akin to the hallmark effects associated with a superfluid, in particular persistent, quantized circulation of the fluid. Using a method proposed by Williams and Holland' we have prepared vortices, macroscopic quantum...
Summary form only given. Magneto-optic trapping of Yb is facilitated by use of a strong transition of the 555.6 nm (6s/sup 2/)/sup 1/S/sub 0/-(6s6p)/sup 3/P/sub 1/ inter-combination line. This line is not radiatively closed, however, and some the decay channels terminate in metastable states, resulting in magneto-optic trapping (MOT) lifetimes that depend on the fraction of atoms in the upper level...
Summary form only given. A chain of ions in a linear trap is ideally suited to process quantum information. Two long-lived internal states in each ion store the quantum bits, which may be coupled by means of the collective vibrational excitation of the chain. A prerequisite for realizing even the simplest two-bit quantum gate is cooling the vibrational degrees of freedom of the ion crystal to the...
Summary form only given. Bose-Einstein condensed atomic gases are a new class of quantum fluids with many novel properties. We have studied collective modes and dissipation by perturbing the condensate with focused laser beams. The scattering of photons imparts momentum to the condensate and creates excitations. Consequently, the coherence and collective behavior of the condensate can strongly affect...
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