10,759 research outputs found
A conditional quantum phase gate between two 3-state atoms
We propose a scheme for conditional quantum logic between two 3-state atoms
that share a quantum data-bus such as a single mode optical field in cavity QED
systems, or a collective vibrational state of trapped ions. Making use of
quantum interference, our scheme achieves successful conditional phase
evolution without any real transitions of atomic internal states or populating
the quantum data-bus. In addition, it only requires common addressing of the
two atoms by external laser fields.Comment: 8 fig
Dipolar effect in coherent spin mixing of two atoms in a single optical lattice site
We show that atomic dipolar effects are detectable in the system that
recently demonstrated two-atom coherent spin dynamics within individual lattice
sites of a Mott state. Based on a two-state approximation for the two-atom
internal states and relying on a variational approach, we have estimated the
spin dipolar effect. Despite the absolute weakness of the dipole-dipole
interaction, it is shown that it leads to experimentally observable effects in
the spin mixing dynamics.Comment: 4 pages, 3 color eps figures, to appear in Phys. Rev. Let
A single intrinsic Josephson junction with double-sided fabrication technique
We make stacks of intrinsic Josephson junctions (IJJs) imbedded in the bulk
of very thin (~nm) single crystals.
By precisely controlling the etching depth during the double-sided fabrication
process, the stacks can be reproducibly tailor-made to be of any microscopic
height (), i.e. enclosing a specified number of IJJ (0-6),
including the important case of a single junction. We discuss reproducible
gap-like features in the current-voltage characteristics of the samples at high
bias.Comment: 3 pages, 4 figures, to be published in APL May. 2
Suppression of the superconducting energy gap in intrinsic Josephson junctions of single crystals
We have observed back-bending structures at high bias current in the
current-voltage curves of intrinsic Josephson junctions. These structures may
be caused by nonequilibrium quasiparticle injection and/or Joule heating. The
energy gap suppression varies considerably with temperature. Different levels
of the suppression are observed when the same level of current passes through
top electrodes of different sizes. Another effect which is seen and discussed,
is a super-current ``reentrance'' of a single intrinsic Josephson junction with
high bias current.Comment: accepted by Supercond. Sci. and Tech., 200
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