1,484 research outputs found
Generation of a spin-polarized electron beam by multipoles magnetic fields
The propagation of an electron beam in the presence of transverse magnetic
fields possessing integer topological charges is presented. The spin--magnetic
interaction introduces a nonuniform spin precession of the electrons that gains
a space-variant geometrical phase in the transverse plane proportional to the
field's topological charge, whose handedness depends on the input electron's
spin state. A combination of our proposed device with an electron orbital
angular momentum sorter can be utilized as a spin-filter of electron beams in a
mid-energy range. We examine these two different configurations of a partial
spin-filter generator numerically. The results of these analysis could prove
useful in the design of improved electron microscope.Comment: 7 pages, 7 figure
Integrated multi vector vortex beam generator
A novel method to generate and manipulate vector vortex beams in an
integrated, ring resonator based geometry is proposed. We show numerically that
a ring resonator, with an appropriate grating, addressed by a vertically
displaced access waveguide emits a complex optical field. The emitted beam
possesses a specific polarization topology, and consequently a transverse
intensity profile and orbital angular momentum. We propose a combination of
several concentric ring resonators, addressed with different bus guides, to
generate arbitrary orbital angular momentum qudit states, which could
potentially be used for classical and quantum communications. Finally, we
demonstrate numerically that this device works as an orbital angular momentum
sorter with an average cross-talk of -10 dB between different orbital angular
momentum channels.Comment: 8 pages, 7 figure
Wrapped branes as qubits
Recent work has established a correspondence between the tripartite
entanglement measure of three qubits and the macroscopic entropy of the
four-dimensional 8-charge STU black hole of supergravity. Here we consider the
configurations of intersecting D3-branes, whose wrapping around the six compact
dimensions T^6 provides the microscopic string-theoretic interpretation of the
charges, and associate the three-qubit basis vectors |ABC>, (A,B,C=0 or 1) with
the corresponding 8 wrapping cycles. In particular, we relate a well-known fact
of quantum information theory, that the most general real three-qubit state can
be parameterized by four real numbers and an angle, to a well-known fact of
string theory, that the most general STU black hole can be described by four
D3-branes intersecting at an angle.Comment: Version appearing in Phys. Rev. Lett, includes Type IIA description
as well as Type II
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