77,761 research outputs found
Wave packet transmission of Bloch electron manipulated by magnetic field
We study the phenomenon of wave packet revivals of Bloch electrons and
explore how to control them by a magnetic field for quantum information
transfer. It is showed that the single electron system can be modulated into a
linear dispersion regime by the "quantized" flux and then an electronic wave
packet with the components localized in this regime can be transferred without
spreading. This feature can be utilized to perform the high-fidelity transfer
of quantum information encoded in the polarization of the spin. Beyond the
linear approximation, the re-localization and self-interference occur as the
novel phenomena of quantum coherence.Comment: 6 pages, 5 figures, new content adde
Quantum state swapping via qubit network with Hubbard interaction
We study the quantum state transfer (QST) in a class of qubit network with
on-site interaction, which is described by the generalized Hubbard model with
engineered couplings. It is proved that the system of two electrons with
opposite spins in this quantum network of sites can be rigorously reduced
into one dimensional engineered single Bloch electron models with central
potential barrier. With this observation we find that such system can perform a
perfect QST, the quantum swapping between two distant electrons with opposite
spins. Numerical results show such QST and the resonant-tunnelling for the
optimal on-site interaction strengths.Comment: 4 pages, 3 figure
Berryogenesis: self-induced Berry flux and spontaneous non-equilibrium magnetism
Spontaneous symmetry breaking is central to the description of interacting
phases of matter. Here we reveal a new mechanism through which a driven
interacting system subject to a time-reversal symmetric driving field can
spontaneously magnetize. We show that the strong internal ac fields of a metal
driven close to its plasmon resonance may enable Berryogenesis: the spontaneous
generation of a self-induced Bloch band Berry flux. The self-induced Berry flux
supports and is sustained by a circulating plasmonic motion, which may arise
even for a linearly polarized driving field. This non-equilibrium phase
transition occurs above a critical driving amplitude, and may be of either
continuous or discontinuous type. Berryogenesis relies on feedback due to
interband coherences induced by internal fields, and may readily occur in a
wide variety of multiband systems. We anticipate that graphene devices, in
particular, provide a natural platform to achieve Berryogenesis and
plasmon-mediated spontaneous non-equilibrium magnetization in present-day
devices
Energy-driven Drag at Charge Neutrality in Graphene
Coulomb coupling between proximal layers in graphene heterostructures results
in efficient energy transfer between the layers. We predict that, in the
presence of correlated density inhomogeneities in the layers, vertical energy
transfer has a strong impact on lateral charge transport. In particular, for
Coulomb drag it dominates over the conventional momentum drag near zero doping.
The dependence on doping and temperature, which is different for the two drag
mechanisms, can be used to separate these mechanisms in experiment. We predict
distinct features such as a peak at zero doping and a multiple sign reversal,
which provide diagnostics for this new drag mechanism.Comment: 6 pgs, 3 fg
A probe of the Radion-Higgs mixing in the Randall-Sundrum model at e^+ e^- colliders
In the Randall-Sundrum model, the radion-Higgs mixing is weakly suppressed by
the effective electroweak scale. A novel feature of the existence of
gravity-scalar mixing would be a sizable three-point vertex among the KK
graviton, Higgs and radion. We study this vertex in the process e^+ e^- -> h
phi, which is allowed only with a non-zero radion-Higgs mixing. It is shown
that the angular distribution is a unique characteristic of the exchange of
massive spin-2 gravitons, and the total cross section at the future e^+ e^-
collider is big enough to cover a large portion of the parameter space where
the LEP/LEP II data cannot constrain.Comment: 14pages, RevTeX, 5 figure
Chiral plasmons without magnetic field
Plasmons, the collective oscillations of interacting electrons, possess
emergent properties that dramatically alter the optical response of metals. We
predict the existence of a new class of plasmons -- chiral Berry plasmons
(CBPs) -- for a wide range of two-dimensional metallic systems including gapped
Dirac materials. As we show, in these materials the interplay between Berry
curvature and electron-electron interactions yields chiral plasmonic modes at
zero magnetic field. The CBP modes are confined to system boundaries, even in
the absence of topological edge states, with chirality manifested in split
energy dispersions for oppositely directed plasmon waves. We unveil a rich CBP
phenomenology and propose setups for realizing them, including in anomalous
Hall metals and optically-pumped 2D Dirac materials. Realization of CBPs will
offer a new paradigm for magnetic field-free, sub-wavelength optical
non-reciprocity, in the mid IR-THz range, with tunable splittings as large as
tens of THz, as well as sensitive all-optical diagnostics of topological bands.Comment: 10 pgs, 3 fg
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