61 research outputs found
Dynamic scaling form in wavelet-discriminated Edwards-Wilkinson growth equation
We present an analysis of dynamic scaling of the Edwards-Wilkinson growth model from wavelets' perspective. Scaling function for the surface width is determined using wavelets' formalism, by computing the surface width for each wavelet scale, we show that an exact and simple form of the scaling function is obtained. These predictions are confirmed by computer simulation of a growth model described by the EW equation, and by numerical calculations
Roughness with a finite correlation length in the Microtrap
We analyze the effects of roughness in the magnitude of the magnetic field
produced by a current carrying microwire, which is caused by geometric
fluctuation of the edge of wire. The relation between the fluctuation of the
trapping potential and the height that atom trap lies above the wire is
consistent with the experimental data very well, when the colored noise with a
finite correlation length is considered. On this basis, we generate the random
potential and get the density distribution of the BEC atoms by solving the
Gross-Pitaevskii equation, which coincides well with the experimental image,
especially in the number of fragmentations. The results help us further
understand the nature of the fluctuation and predict the possible application
in the precise measurement.Comment: 6 pages, 7 figure
The effect of self-affine fractal roughness of wires on atom chips
Atom chips use current flowing in lithographically patterned wires to produce
microscopic magnetic traps for atoms. The density distribution of a trapped
cold atom cloud reveals disorder in the trapping potential, which results from
meandering current flow in the wire. Roughness in the edges of the wire is
usually the main cause of this behaviour. Here, we point out that the edges of
microfabricated wires normally exhibit self-affine roughness. We investigate
the consequences of this for disorder in atom traps. In particular, we consider
how closely the trap can approach the wire when there is a maximum allowable
strength of the disorder. We comment on the role of roughness in future
atom--surface interaction experiments.Comment: 7 pages, 7 figure
Fabrication of micromirrors with pyramidal shape using anisotropic etching of silicon
Gold micro-mirrors have been formed in silicon in an inverted pyramidal shape. The pyramidal structures are created in the (100) surface of a silicon wafer by anisotropic etching in potassium hydroxide. High quality micro-mirrors are then formed by sputtering gold onto the smooth silicon (111) faces of the pyramids. These mirrors show great promise as high quality optical devices suitable for integration into MOEMS systems
Microfabricated high-finesse optical cavity with open access and small volume
We present a microfabricated optical cavity, which combines a very small mode volume with high finesse. In contrast to other micro-resonators, such as microspheres, the structure we have built gives atoms and molecules direct access to the high-intensity part of the field mode, enabling them to interact strongly with photons in the cavity for the purposes of detection and quantum-coherent manipulation. Light couples directly in and out of the resonator through an optical fiber, avoiding the need for sensitive coupling optics. This renders the cavity particularly attractive as a component of a lab-on-a-chip, and as a node in a quantum network
Atom chip for BEC interferometry
We have fabricated and tested an atom chip that operates as a matter wave interferometer. In this communication we describe the fabrication of the chip by ion-beam milling of gold evaporated onto a silicon substrate. We present data on the quality of the wires, on the current density that can be reached in the wires and on the smoothness of the magnetic traps that are formed. We demonstrate the operation of the interferometer, showing that we can coherently split and recombine a Bose–Einstein condensate with good phase stability
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