1,824 research outputs found
Nearly Deterministic Bell Measurement for Multiphoton Qubits and Its Application to Quantum Information Processing
We propose a Bell measurement scheme by employing a logical qubit in
Greenberger-Horne-Zeilinger (GHZ) entanglement with an arbitrary number of
photons. Remarkably, the success probability of the Bell measurement as well as
teleportation of the GHZ entanglement can be made arbitrarily high using only
linear optics elements and photon on-off measurements as the number of photons
increases. Our scheme outperforms previous proposals using single photon qubits
when comparing the success probabilities in terms of the average photon usages.
It has another important advantage for experimental feasibility that it does
not require photon number resolving measurements. Our proposal provides an
alternative candidate for all-optical quantum information processing.Comment: 7 pages (including supplementary material), 2 figures, to be
published in Phys. Rev. Let
Curvature-enhanced spin-orbit coupling in a carbon nanotube
Structure of the spin-orbit coupling varies from material to material and
thus finding the correct spin-orbit coupling structure is an important step
towards advanced spintronic applications. We show theoretically that the
curvature in a carbon nanotube generates two types of the spin-orbit coupling,
one of which was not recognized before. In addition to the topological
phase-related contribution of the spin-orbit coupling, which appears in the
off-diagonal part of the effective Dirac Hamiltonian of carbon nanotubes, there
is another contribution that appears in the diagonal part. The existence of the
diagonal term can modify spin-orbit coupling effects qualitatively, an example
of which is the electron-hole asymmetric spin splitting observed recently, and
generate four qualitatively different behavior of energy level dependence on
parallel magnetic field. It is demonstrated that the diagonal term applies to a
curved graphene as well. This result should be valuable for spintronic
applications of graphitic materials.Comment: 6 pages, 4 figures, to be published on Physical Review
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