2,147 research outputs found
A scheme for tunable quantum phase gate and effective preparation of graph-state entanglement
A scheme is presented for realizing a quantum phase gate with three-level
atoms, solid-state qubits--often called artificial atoms, or ions that share a
quantum data bus such as a single mode field in cavity QED system or a
collective vibrational state of trapped ions. In this scheme, the conditional
phase shift is tunable and controllable via the total effective interaction
time. Furthermore, we show that the method can be used for effective
preparation of graph-state entanglement, which are important resources for
quantum computation, quantum error correction, studies of multiparticle
entanglement, fundamental tests of non-locality and decoherence.Comment: 7 pages, 5 figure
Gluon Condensation Signature in the GeV Gamma-Ray Spectra of Pulsars
The accumulation of gluons inside nucleons, i.e., the gluon condensation, may
lead to a characteristic broken power-law gamma-ray spectrum in high-energy
nucleon collisions. Here we show that the observed spectra of at least 25
sources in the second Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
can be well fitted by such a broken power-law function that has only four free
parameters. It strongly indicates that the gamma-ray emission from these
pulsars is of hadronic origin, but with gluon condensation inside hadrons. It
is well known that the quark-gluon distribution in a free nucleon is different
from that in a bound nucleon. This work exposes the nuclear -dependence of
the gluon condensation effect, where refers to the baryon number. Our study
reveals the gluon condensation under the condition of , which may
open a new window for eavesdropping on the structure of compact stars on the
sub-nuclear level.Comment: 12 pages (9 pages for main text), 5 figures, 1 table, accepted by PRD
at
https://journals.aps.org/prd/accepted/fd07cQ89M2118d20490d0d014fdd00616d4cdeb8
High visibility on-chip quantum interference of single surface plasmons
Quantum photonic integrated circuits (QPICs) based on dielectric waveguides
have been widely used in linear optical quantum computation. Recently, surface
plasmons have been introduced to this application because they can confine and
manipulate light beyond the diffraction limit. In this study, the on-chip
quantum interference of two single surface plasmons was achieved using
dielectric-loaded surface-plasmon-polariton waveguides. The high visibility
(greater than 90%) proves the bosonic nature of single plasmons and emphasizes
the feasibility of achieving basic quantum logic gates for linear optical
quantum computation. The effect of intrinsic losses in plasmonic waveguides
with regard to quantum information processing is also discussed. Although the
influence of this effect was negligible in the current experiment, our studies
reveal that such losses can dramatically reduce quantum interference visibility
in certain cases; thus, quantum coherence must be carefully considered when
designing QPIC devices.Comment: 6 pages, 4 figure
Topological magnons in one-dimensional ferromagnetic Su-Schrieffer-Heeger model with anisotropic interaction
Topological magnons in a one-dimensional (1D) ferromagnetic (FM)
Su-Schrieffer-Heeger (SSH) model with anisotropic exchange interactions are
investigated. Apart from the inter-cellular isotropic Heisenberg interaction,
the intercellular anisotropic exchange interactions, i.e. Dzyaloshinskii-Moriya
interaction (DMI) and pseudo-dipolar interaction (PDI), also can induce the
emergence of the non-trivial phase with two degenerate in-gap edge states
separately localized at the two ends of the 1D chain, while the intracellular
interactions instead unfavors the topological phase. The interplay among them
has synergistic effects on the topological phase transition, very different
from that in the two-dimensional (2D) ferromagnet. These results demonstrate
that the 1D magnons possess rich topological phase diagrams distinctly
different from the electronic version of the SSH model and even the 2D magnons.
Due to the lower dimensional structural characteristics of this 1D topological
magnonic system, the magnonic crystals can be constructed from bottom to top,
which has important potential applications in the design of novel magnonic
devices.Comment: 22 pages, 11 figure
Bacterial Peptidoglycan Triggers Candida albicans Hyphal Growth by Directly Activating the Adenylyl Cyclase Cyr1p
SummaryHuman serum potently induces hyphal development of the polymorphic fungal pathogen Candida albicans, a phenotype that contributes critically to infections. The fungal adenylyl cyclase Cyr1p is a key component of the cAMP/PKA-signaling pathway that controls diverse infection-related traits, including hyphal morphogenesis. However, identity of the serum hyphal inducer(s) and its fungal sensor remain unknown. Our initial analyses of active serum fractions revealed signs of bacterial peptidoglycan (PGN)-like molecules. Here, we show that several purified and synthetic muramyl dipeptides (MDPs), subunits of PGN, can strongly promote C. albicans hyphal growth. Analogous to PGN recognition by the mammalian sensors Nod1 and Nod2 through their leucine-rich-repeat (LRR) domain, we show that MDPs activate Cyr1p by directly binding to its LRR domain. Given the abundance of PGN in the intestine, a natural habitat and invasion site for C. albicans, our findings have important implications for the mechanisms of infection by this pathogen
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