60 research outputs found
The anomalous Hall conductivity due to the vector spin chirality
We study theoretically the anomalous Hall effect due to the vector spin
chirality carried by the local spins in the - model. We will show that
the vector spin chirality indeed induces local Hall effect in the presence of
the electron spin polarization, while the global Hall effect vanishes if
electron transport is homogeneous. This anomalous Hall effect can be
interpreted in terms of the rotational component of the spin current associated
with the vector chirality.Comment: 12 pages, 5 figure
Spin relaxation torque in metallic ferromagnets
Spin relaxation torque in uniform metallic ferromagnets with the
spin-orbit interaction arising from random impurities is calculated
microscopically. is shown to be written by spatial derivatives of
the electric field, but is not always given as a divergence of a torque dipole
density. The result is due to the fast dissipation of the orbital angular
momentum, and thus a conserving spin current cannot be defined. It is discussed
that the term in the spin transfer torque can also be asymmetric
Ultrafast magnetic vortex core switching driven by topological inverse Faraday effect
We present a theoretical discovery of an unconventional mechanism of inverse
Faraday effect (IFE) which acts selectively on topological magnetic structures.
The effect, topological inverse Faraday effect (TIFE), is induced by spin
Berry's phase of the magnetic structure when a circularly polarized light is
applied. Thus a spin-orbit interaction is not necessary unlike in the
conventional IFE. We demonstrate by numerical simulation that TIFE realizes
ultrafast switching of a magnetic vortex within a switching time of 150 ps
without magnetic field.Comment: 11 pages, 4 figure
Measurement and control of spatial qubits generated by passing photons through double-slits
We present an experimental study of the non-classical correlations of a pair
of spatial qubits formed by passing two down-converted photons through a pair
of double slits. After confirming the entanglement generated in our setup by
quantum tomography using separate measurements of the slit images and the
interference patterns, we show that the complete Hilbert space of the spatial
qubits can be accessed by measurements performed in a single plane between the
image plane and the focal plane of a lens. Specifically, it is possible to
obtain both the which-path and the interference information needed for quantum
tomography in a single scan of the transversal distribution of photon
coincidences. Since this method can easily be extended to multi-dimensional
systems, it may be a valuable tool in the application of spatial qudits to
quantum information processes.Comment: 19 pages, including 10 figures and 2 table
Mechanical active control of surface plasmon properties
We present a multilayer device which allows the control of Surface Plasmon (SP) propagation properties (propagation length and extension). A simple modification on an inner air gap thickness strongly affects SP propagation mode due to coupling with Parallel-Plate (PP) mode
The effect of pCO2 on size-fractionated phytoplankton community in the Southern Ocean
第3回極域科学シンポジウム 横断セッション「南極海季節的海氷域における生物地球化学」11月26日(月) 統計数理研究所 セミナー
Weak measurement of photon polarization by back-action induced path interference
The essential feature of weak measurements on quantum systems is the
reduction of measurement back-action to negligible levels. To observe the
non-classical features of weak measurements, it is therefore more important to
avoid additional back-action errors than it is to avoid errors in the actual
measurement outcome. In this paper, it is shown how an optical weak measurement
of diagonal (PM) polarization can be realized by path interference between the
horizontal (H) and vertical (V) polarization components of the input beam. The
measurement strength can then be controlled by rotating the H and V
polarizations towards each other. This well-controlled operation effectively
generates the back-action without additional decoherence, while the visibility
of the interference between the two beams only limits the measurement
resolution. As the experimental results confirm, we can obtain extremely high
weak values, even at rather low visibilities. Our method therefore provides a
realization of weak measurements that is extremely robust against experimental
imperfections.Comment: 11 pages, 3 figure
Permanent current from non-commutative spin algebra
We show that a spontaneous electric current is induced in a nano-scale
conducting ring just by putting three ferromagnets. The current is a direct
consequence of the non-commutativity of the spin algebra, and is proportional
to the non-coplanarity (chirality) of the magnetization vectors. The
spontaneous current gives a natural explanation to the chirality-driven
anomalous Hall effect.Comment: 7 pages, 4 figures on separate pag
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