9,495 research outputs found
Cogeneration of Dark Matter and Baryons by Non-Standard-Model Sphalerons in Unified Models
Sphalerons of a new gauge interaction can convert a primordial asymmetry in B
or L into a dark matter asymmetry. From the equilibrium conditions for the
sphalerons of both the electroweak and the new interactions, one can compute
the ratios of B, L, and X, where X is the dark matter number, thus determining
the mass of the dark matter particle fairly precisely. Such a scenario can
arise naturally in the context of unification with larger groups. An
illustrative model embeddable in is described
as well as an equally simple model based on SU(7).Comment: 13 pages. Revised introduction and references, changed titl
An Evidence Based Time-Frequency Search Method for Gravitational Waves from Pulsar Glitches
We review and expand on a Bayesian model selection technique for the
detection of gravitational waves from neutron star ring-downs associated with
pulsar glitches. The algorithm works with power spectral densities constructed
from overlapping time segments of gravitational wave data. Consequently, the
original approach was at risk of falsely identifying multiple signals where
only one signal was present in the data. We introduce an extension to the
algorithm which uses posterior information on the frequency content of detected
signals to cluster events together. The requirement that we have just one
detection per signal is now met with the additional bonus that the belief in
the presence of a signal is boosted by incorporating information from adjacent
time segments.Comment: 6 pages, 4 figures, submitted to AMALDI 7 proceeding
A Naturally Minute Quantum Correction to the Cosmological Constant Descended from the Hierarchy
We demonstrate that an extremely small but positive quantum correction, or
the Casimir energy, to the cosmological constant can arise from a massive bulk
fermion field in the Randall-Sundrum model. Specifically, a cosmological
constant doubly descended from the Planck-electroweak hierarchy and as minute
as the observed dark energy scale can be naturally achieved without fine-tuning
of the bulk fermion mass. To ensure the stabilization of the system, we discuss
two stabilization mechanisms under this setup. It is found that the
Goldberger-Wise mechanism can be successfully introduced in the presence of a
massive bulk fermion, without spoiling the smallness of the quantum correction.Comment: 5 page
Null-stream veto for two co-located detectors: Implementation issues
Time-series data from multiple gravitational wave (GW) detectors can be
linearly combined to form a null-stream, in which all GW information will be
cancelled out. This null-stream can be used to distinguish between actual GW
triggers and spurious noise transients in a search for GW bursts using a
network of detectors. The biggest source of error in the null-stream analysis
comes from the fact that the detector data are not perfectly calibrated. In
this paper, we present an implementation of the null-stream veto in the
simplest network of two co-located detectors. The detectors are assumed to have
calibration uncertainties and correlated noise components. We estimate the
effect of calibration uncertainties in the null-stream veto analysis and
propose a new formulation to overcome this. This new formulation is
demonstrated by doing software injections in Gaussian noise.Comment: Minor changes; To appear in Class. Quantum Grav. (Proc. GWDAW10
Quantum information approach to the quantum phase transition in the Kitaev honeycomb model
Kitaev honeycomb model with topological phase transition at zero temperature
is studied using quantum information method. Based on the exact solution of the
ground state, the mutual information between two nearest sites and between two
bonds with longest distance are obtained. It is found that the mutual
information show some singularities at the critical point where the ground
state of the system transits from gapless phase to gapped phase. The
finite-size effects and scalar behavior are also studied. The mutual
information can serve as good indicators of the topological phase transition,
since the mutual information catches some global correlation properties of the
system. Meanwhile, this method has other advantages such that the phase
transition can be determined easily and the order parameters are not required
previously, for the order parameters of some topological phase transitions are
hard to know.Comment: 8 pages, 7 figures, published versio
Entanglement in a Valence-Bond-Solid State
We study entanglement in Valence-Bond-Solid state. It describes the ground
state of Affleck, Kennedy, Lieb and Tasaki quantum spin chain. The AKLT model
has a gap and open boundary conditions. We calculate an entropy of a subsystem
(continuous block of spins). It quantifies the entanglement of this block with
the rest of the ground state. We prove that the entanglement approaches a
constant value exponentially fast as the size of the subsystem increases.
Actually we proved that the density matrix of the continuous block of spins
depends only on the length of the block, but not on the total size of the chain
[distance to the ends also not essential]. We also study reduced density
matrices of two spins both in the bulk and on the boundary. We evaluated
concurrencies.Comment: 4pages, no figure
OPTIMIZATION OF SCREEN PRINTED REFERENCE ELECTRODE BASED ON CHARGE BALANCE AND POLY (BUTYL ACRYLATE) PHOTOCURABLE MEBRANE
This research focus on transforming the traditional design of reference electrode into all-solid-state reference electrode front-end using Ag/AgCl screen- printed electrodes. By replacing the internal reference solution of a traditional reference electrode by a solid photocurable membrane, an all-solid-state reference electrode can be achieved. The solid-state screen-printed reference electrode was designed using a photocurable acrylic film containing immobilized sodium tetrakis [3,5-bis(trifluoromethyl)phenyl] borate (NaTFPB) and trimethylocthylammonium chloride (TOMA-Cl). An optimum ratio of NaTFPB:TOMA-Cl = 1:1 produced a stable reference electrode. In the anions interference studies, all anions i.e. NO3-, Cl-, Br- and SO42- does not give effect to the SPRE except perchlorate anions. The all-solid-state reference electrodes was applied to the detection of potassium ions and ammonium ions. Validation of the all-screen-printed reference electrode was performed with reference electrode standard gel type. The validation results showed that all-solid-state screen-printed reference electrode demonstrated performance that was comparable to standard reference electrode
OPTIMIZATION OF SCREEN PRINTED REFERENCE ELECTRODE BASED ON CHARGE BALANCE AND POLY (BUTYL ACRYLATE) PHOTOCURABLE MEBRANE
This research focus on transforming the traditional design of reference electrode into all-solid-state reference electrode front-end using Ag/AgCl screen- printed electrodes. By replacing the internal reference solution of a traditional reference electrode by a solid photocurable membrane, an all-solid-state reference electrode can be achieved. The solid-state screen-printed reference electrode was designed using a photocurable acrylic film containing immobilized sodium tetrakis [3,5-bis(trifluoromethyl)phenyl] borate (NaTFPB) and trimethylocthylammonium chloride (TOMA-Cl). An optimum ratio of NaTFPB:TOMA-Cl = 1:1 produced a stable reference electrode. In the anions interference studies, all anions i.e. NO3-, Cl-, Br- and SO42- does not give effect to the SPRE except perchlorate anions. The all-solid-state reference electrodes was applied to the detection of potassium ions and ammonium ions. Validation of the all-screen-printed reference electrode was performed with reference electrode standard gel type. The validation results showed that all-solid-state screen-printed reference electrode demonstrated performance that was comparable to standard reference electrode.
Deterministic quantum teleportation between distant atomic objects
Quantum teleportation is a key ingredient of quantum networks and a building
block for quantum computation. Teleportation between distant material objects
using light as the quantum information carrier has been a particularly exciting
goal. Here we demonstrate a new element of the quantum teleportation landscape,
the deterministic continuous variable (cv) teleportation between distant
material objects. The objects are macroscopic atomic ensembles at room
temperature. Entanglement required for teleportation is distributed by light
propagating from one ensemble to the other. Quantum states encoded in a
collective spin state of one ensemble are teleported onto another ensemble
using this entanglement and homodyne measurements on light. By implementing
process tomography, we demonstrate that the experimental fidelity of the
quantum teleportation is higher than that achievable by any classical process.
Furthermore, we demonstrate the benefits of deterministic teleportation by
teleporting a dynamically changing sequence of spin states from one distant
object onto another
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