111 research outputs found
A lattice of microtraps for ultracold atoms based on patterned magnetic films
We have realized a two dimensional permanent magnetic lattice of
Ioffe-Pritchard microtraps for ultracold atoms. The lattice is formed by a
single 300 nm magnetized layer of FePt, patterned using optical lithography.
Our magnetic lattice consists of more than 15000 tightly confining microtraps
with a density of 1250 traps/mm. Simple analytical approximations for the
magnetic fields produced by the lattice are used to derive relevant trap
parameters. We load ultracold atoms into at least 30 lattice sites at a
distance of approximately 10 m from the film surface. The present result
is an important first step towards quantum information processing with neutral
atoms in magnetic lattice potentials.Comment: 7 pages, 7 figure
Fabrication of magnetic atom chips based on FePt
We describe the design and fabrication of novel all-magnetic atom chips for
use in ultracold atom trapping. The considerations leading to the choice of
nanocrystalline exchange coupled FePt as best material are discussed. Using
stray field calculations, we designed patterns that function as magnetic atom
traps. These patterns were realized by spark erosion of FePt foil and e-beam
lithography of FePt film. A mirror magneto-optical trap (MMOT) was obtained
using the stray field of the foil chip.Comment: 5 pages, 5 figure
Pseudogap-less high T superconductivity in BaCoFeAs
The pseudogap state is one of the peculiarities of the cuprate high
temperature superconductors. Here we investigate its presence in
BaCoFeAs, a member of the pnictide family, with temperature
dependent scanning tunneling spectroscopy. We observe that for under, optimally
and overdoped systems the gap in the tunneling spectra always closes at the
bulk T, ruling out the presence of a pseudogap state. For the underdoped
case we observe superconducting gaps over large fields of view, setting a lower
limit of tens of nanometers on the length scale of possible phase separated
regions.Comment: 5 pages, 3 figure
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