We give a comprehensive overview of the development of micro traps, from the first experiments on guiding atoms using current carrying wires in the early 1990's to the creation of a BEC on an atom chip.

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We derive the life time and loss rate for a trapped atom that is coupled to fluctuating fields in the vicinity of a room-temperature metallic and/or dielectric surface. Our results indicate a clear predominance of near field effects over ordinary blackbody radiation. We develop a theoretical framework for both charged ions and neutral atoms with and without spin. Loss processes that are due to a transition to an untrapped internal state are included.

We study the heat transfer between two parallel metallic semi-infinite media with a gap in the nanometer-scale range. We show that the near-field radiative heat flux saturates at distances smaller than the metal skin depth when using a local dielectric constant and investigate the origin of this effect. The effect of non-local corrections is analysed using the Lindhard-Mermin and Boltzmann-Mermin models. We find that local and non-local models yield the same heat fluxes for gaps larger than 2 nm. Finally, we explain the saturation observed in a recent experiment as a manifestation of the skin depth and show that heat is mainly dissipated by eddy currents in metallic bodies.

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The existing optical microscopes form an image by collecting photons emitted from an object. Here we report on the experimental realization of microscopy without the need for direct optical communication with the sample. To achieve this, we have scanned a single gold nanoparticle acting as a nano-antenna in the near field of a sample and have studied the modification of its intrinsic radiative properties by monitoring its plasmon spectrum.PACS numbers: 07.79. Fc, 42.50.Lc, 78.67.Bf Over the years, several clever techniques such as darkfield, phase contrast, fluorescence, differential interference contrast, confocal, and scanning near-field microscopies have provided powerful ways of performing optical imaging. In all these methods, as in any other visual process, one "sees" an object when photons originating from it reach the detector. The details of the imaging mechanism depend sensitively on the intensity, phase and polarization of light both in the illumination and collection channels. The thought of recording optical images without receiving photons from the object, therefore, seems to be a contradiction in terms. In this Letter we show that this is indeed possible if one monitors the intrinsic spectral properties of a nanoscopic antenna scanned close to the sample.When an oscillating dipole is placed in confined geometries its radiative properties, such as eigenfrequency and linewidth, are modified [1,2]. In an intuitive picture these modifications are due to the interaction of the oscillating dipole with its image dipoles whereby the boundary materials and their distances to the oscillator determine the strength and phase of this interaction. In an alternative point of view the radiative changes are due to the modification of the density of photon states available for emission. In the context of recent developments in nano-optics, theoretical investigations have extended these concepts to subwavelength geometries and have shown that the linewidth [3,4,5,6,7] and the transition frequency [5,6] of a dipole also respond sensitively to the optical contrast of its nanoscopic environment.

We analyze the spatial coherence of the electromagnetic field emitted by a half-space at temperature T close to the interface. An asymptotic analysis allows to identify three different contributions to the cross-spectral density tensor in the near-field regime. It is shown that the coherence length can be either much larger or much shorter than the wavelength depending on the dominant contribution.Comment: 13 pages, 8 graphs, includes Elsevier elsart.cls preprint style. Submitted to Optics Communications (27 july 2000

We analyze the equilibrium properties of a weakly interacting, trapped quasi-one-dimensional Bose gas at finite temperatures and compare different theoretical approaches. We focus in particular on two stochastic theories: a number-conserving Bogoliubov (ncB) approach and a stochastic GrossPitaevskii equation (sGPe) that have been extensively used in numerical simulations. Equilibrium properties like density profiles, correlation functions, and the condensate statistics are compared to predictions based upon a number of alternative theories. We find that due to thermal phase fluctuations, and the corresponding condensate depletion, the ncB approach loses its validity at relatively low temperatures. This can be attributed to the change in the Bogoliubov spectrum, as the condensate gets thermally depleted, and to large fluctuations beyond perturbation theory. Although the two stochastic theories are built on different thermodynamic ensembles (ncB: canonical, sGPe: grandcanonical), they yield the correct condensate statistics in a large BEC (strong enough particle interactions). For smaller systems, the sGPe results are prone to anomalously large number fluctuations, well-known for the grand-canonical, ideal Bose gas. Based on the comparison of the above theories to the modified Popov approach, we propose a simple procedure for approximately extracting the Penrose-Onsager condensate from first-and second-order correlation functions that is computationally convenient. This also clarifies the link between condensate and quasi-condensate in the Popov theory of low-dimensional systems.