81,186 research outputs found
R-mode instability in compact stars
R-mode oscillations have been identified as viable and promising targets for
continuous gravitational wave searches, meanwhile, it would allow us to probe
the interior of compact stars directly. As well as emitting gravitational wave,
r-modes would strongly affect the thermal and spin evolution of compact stars.
In this paper, we reviewed the theory behind the gravitational wave driven
r-mode instability in a rapidly rotating compact star. In particular, we will
focus on r-mode instability window, r-mode evolution and detectability of
r-mode.Comment: contribution to the AIP Proceedings of the Xiamen-CUSTIPEN Workshop
on the EOS of Dense Neutron-Rich Matter in the Era of Gravitational Wave
Astronomy, Jan. 3-7, 2019, Xiamen, China. arXiv admin note: text overlap with
arXiv:0806.1005, arXiv:1510.07051, arXiv:1209.5962 by other author
Isobaric Reconstruction of the Baryonic Acoustic Oscillation
In this paper, we report a significant recovery of the linear baryonic
acoustic oscillation (BAO) signature by applying the isobaric reconstruction
algorithm to the non-linear matter density field. Assuming only the
longitudinal component of the displacement being cosmologically relevant, this
algorithm iteratively solves the coordinate transform between the Lagrangian
and Eulerian frames without requiring any specific knowledge of the dynamics.
For dark matter field, it produces the non-linear displacement potential with
very high fidelity. The reconstruction error at the pixel level is within a few
percent, and is caused only by the emergence of the transverse component after
the shell-crossing. As it circumvents the strongest non-linearity of the
density evolution, the reconstructed field is well-described by linear theory
and immune from the bulk-flow smearing of the BAO signature. Therefore this
algorithm could significantly improve the measurement accuracy of the sound
horizon scale. For a perfect large-scale structure survey at redshift zero
without Poisson or instrumental noise, the fractional error is reduced by a
factor of 2.7, very close to the ideal limit with linear power spectrum and
Gaussian covariance matrix.Comment: 5 pages, 3 figures, accepted versio
Computational Design of Flexible Electride with Nontrivial Band Topology
Electrides, with their excess electrons distributed in crystal cavities playing the role of anions, exhibit a variety of unique electronic and magnetic properties. In this work, we employ the first-principles crystal structure prediction to identify a new prototype of A3B electride in which both interlayer spacings and intralayer vacancies provide channels to accommodate the excess electrons in the crystal. This A3B type of structure is calculated to be thermodynamically stable for two alkaline metals oxides (Rb3O and K3O). Remarkably, the unique feature of multiple types of cavities makes the spatial arrangement of anionic electrons highly flexible via elastic strain engineering and chemical substitution, in contrast to the previously reported electrides characterized by a single topology of interstitial electrons. More importantly, our first-principles calculations reveal that Rb3O is a topological Dirac nodal line semimetal, which is induced by the band inversion at the general electronic k momentums in the Brillouin zone associated with the intersitial electric charges. The discovery of flexible electride in combining with topological electronic properties opens an avenue for electride design and shows great promises in electronic device applications
Entanglement R\'enyi -entropy
We study the entanglement R\'{e}nyi -entropy (ERE) as the
measure of entanglement. Instead of a single quantity in standard entanglement
quantification for a quantum state by using the von Neumann entropy for the
well-accepted entanglement of formation (EoF), the ERE gives a
continuous spectrum parametrized by variable as the entanglement
measure, and it reduces to the standard EoF in the special case . The ERE provides more information in entanglement
quantification, and can be used such as in determining the convertibility of
entangled states by local operations and classical communication. A series of
new results are obtained: (i) we can show that ERE of two states,
which can be mixed or pure, may be incomparable, in contrast to the fact that
there always exists an order for EoF of two states; (ii) similar as the case of
EoF, we study in a fully analytical way the ERE for arbitrary
two-qubit states, the Werner states and isotropic states in general
d-dimension; (iii) we provide a proof of the previous conjecture for the
analytical functional form of EoF of isotropic states in arbitrary d-dimension.Comment: 11 pages, 4 figure
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