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Summary form only given. During the last decade both, experimentalists and theoreticians, began extensively to investigate ultrafast phenomena as wave packet propagation, coherent control, internal vibrational redistribution, structural relaxation and photodissociation in physical, chemical and biological systems. In particular, the wave packet propagation of small molecules as the potassium dimer...
Summary form only given. We consider the semiclassical orbits of cold atoms in an optical lattice with a magnetically-induced harmonic trap. When the laser beams are aligned with a principal axis of the trap, the atoms follow regular classical paths. But when the laser beams are tilted at an angle to the axis, the atoms undergo a controllable transition from regular motion to strong classical chaos...
Summary form only given. We discuss a means of achieving a large optical nonlinearity in a material on the verge of a transition between structural phases with significantly different optical properties. We have found that films of gallium deposited on fused silica by ultrafast pulsed laser ablation show a fully reversible, surface-assisted metallization when approaching the transition from the /spl...
Summary form only given. Anomalous behaviors of conductivity and/or magnetic properties, which are observed in perovskite transition metal oxides, have attracted much interest recently. In the present paper, we report on a peculiar optical response observed in quasi-one-dimensional (1D) cuprates, Sr/sub 2/CuO/sub 3/ and SrCuO/sub 2/. Femtosecond pump-probe transmission spectra in the 1D cuprates are...
Summary form only given. Atomic matter waves, just like electromagnetic waves, can be focused, reflected, guided and split by the passive atom optical elements of today. However, the key for many applications of RF and light waves lies in the availability of amplifiers. Here, we report the observation of phase coherent amplification of atomic matter waves.
Summary form only given. A distinguishing feature of Bose-Einstein condensates in trapped atomic gases is the ability to manipulate them with laser light. This is a tool which is not available for the study of liquid helium. In this work, we use the mechanical forces exerted by light on atoms to create and study collective excitations. We can apply either repulsive or attractive forces locally to...
Summary form only given. Dark spatial solitons maybe used as configurable waveguides for all-optical switching and interconnecting. However, when many solitons are placed in a periodic array, they may lose their "particle-like identity". In this regime, which may be described in terms of the Floquet theorem (Bloch's theorem), the soliton trajectories are sinuous rather than straight. Furthermore,...
Summary form only given. Modulation instability (MI) is a common phenomenon in coherent non-linear wave systems; it can be typically observed on top of a broad pulse or an optical beam. In this case, small noise perturbations grow exponentially as the pulse propagates, transferring energy from large wavelengths into smaller wavelengths. In a sense, MI phenomena can be regarded as a precursor of bright...
Summary form only given. In order to manufacture a modelocked, pulsed atom laser, we suggest the idea of making use of the atom-atom repulsion in a BEC to form a toroidal soliton which can then form a reproducible, coherent waveform. The relevant solitons have the form of a kink, or phase-singularity in the nonlinear Schrodinger equation. We suppose that the atoms are all trapped in a deep, toroidal...
Summary form only given. One of the most striking results in the field of Bose-Einstein Condensation (BEC) is the possibility of creating an atom laser, using the trapped condensate as a continuously replenished source of a coherent atomic beam. Prototype atom lasers have already been demonstrated experimentally. One fruitful theoretical description is mean field theory, as fully quantised models...
Summary form only given. Magnetic trapping and evaporative cooling have been employed to cool a million /sup 40/K atoms to below the Fermi temperature, T/sub P/. Simultaneous evaporation of spin-mixed samples is used to overcome the lack of s-wave collisions between spin-polarized fermionic atoms at these ultralow temperatures. By releasing the gas from the magnetic trap and allowing it to expand,...
Summary form only given. We report on an experiment performed with a gaseous Bose-Einstein condensate, which is analogous to the rotating bucket experiment performed with liquid He. The atoms are confined in a static, cylindrically symmetric Ioffe-Pritchard magnetic trap upon which we superimpose a nonaxisymmetric, attractive dipole potential created by a stirring laser beam. The combined potential...
Summary form only given. Optical solitons in fibres are attractive macroscopical quantum objects, which are particle-like pulses propagating over large distances without distortion due to the balance between Kerr nonlinearity and group velocity dispersion effects. However, in the frame of the quantum theory, they exhibit a complicated internal quantum structure with nontrivial nonlinear dynamics....
Summary form only given. Greenberger, Horne and Zeilinger have discussed an interesting idealized two-particle double-slit interference experiment. The source is a linear distribution of particles that can decay in two daughter particles. In the decay process, the momenta of the two daughters are approximately equal and opposite. The two double-slits surround the source particle in opposite sides...
Summary form only given. Consider a pair of collinear frequency-degenerate photons-a biphoton, which can be obtained by spontaneous parametric down-conversion (SPDC). Being a three-state quantum system, it is a ternary analog of a qubit. Its state vector is |/spl psi/>=c/sub 1/|2,0>+c/sub 2/|0,2>+c/sub 3/|1,1>, with |n,m>,n+m=2 denoting n X-polarized photons and m Y-polarized photons...
Summary form only given. Quantum cryptographic schemes use fundamental properties of quantum mechanics to ensure the protection of random number keys. In particular the act of measurement in quantum mechanics inevitably disturbs the system. Furthermore, for single quanta such as a photon, simultaneous measurements of non-commuting variables are forbidden. It is of practical and fundamental interest...
Summary form only given. The QKD transmitter, Alice, consists of three diode lasers (a timing laser and two data lasers: one data laser transmits vertical polarized photons, while the other transmits 45 degree polarized photons, two matching interference filters (IF), two optical attenuators, two linear polarizers, two non-polarizing beamsplitters, a 27/spl times/ beam expander, and a single-photon...
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