1,877 research outputs found
Accelerator modes of square well system
We study accelerator modes of a particle, confined in an one-dimensional
infinite square well potential, subjected to a time-periodic pulsed field.
Dynamics of such a particle can be described by one generalization of the
kicked rotor. In comparison with the kicked rotor, this generalization is shown
to have a much larger parametric space for existence of the modes. Using this
freedom we provide evidence that accelerator mode assisted anomalous transport
is greatly enhanced when low order resonances are exposed at the border of
chaos. We also present signature of the enhanced transport in the quantum
domain.Comment: 7 pages, 5 figures, revtex
Characterizing the geometrical edges of nonlocal two-qubit gates
Nonlocal two-qubit gates are geometrically represented by tetrahedron known
as Weyl chamber within which perfect entanglers form a polyhedron. We identify
that all edges of the Weyl chamber and polyhedron are formed by single
parametric gates. Nonlocal attributes of these edges are characterized using
entangling power and local invariants. In particular, SWAP (power)alpha family
of gates constitutes one edge of the Weyl chamber with SWAP-1/2 being the only
perfect entangler. Finally, optimal constructions of controlled-NOT using
SWAP-1/2 gate and gates belong to three edges of the polyhedron are presented.Comment: 11 pages, 4 figures, Phys. Rev. A 79, 052339 (2009
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