33,704 research outputs found
A New Young Diagrammatic Method For Kronecker Products of O(n) and Sp(2m)
A new simple Young diagrammatic method for Kronecker products of O(n) and
Sp(2m) is proposed based on representation theory of Brauer algebras. A general
procedure for the decomposition of tensor products of representations for O(n)
and Sp(2m) is outlined, which is similar to that for U(n) known as the
Littlewood rules together with trace contractions from a Brauer algebra and
some modification rules given by King.Comment: Latex, 11 pages, no figure
Double intelligent reflecting surface-assisted multi-user MIMO mmWave systems with hybrid precoding
This work investigates the effect of double intelligent reflecting surface (IRS) in improving the spectrum efficient of multi-user multiple-input multiple-output (MIMO) network operating in the millimeter wave (mmWave) band. Specifically, we aim to solve a weighted sum rate maximization problem by jointly optimizing the digital precoding at the transmitter and the analog phase shifters at the IRS, subject to the minimum achievable rate constraint. To facilitate the design of an efficient solution, we first reformulate the original problem into a tractable one by exploiting the majorization-minimization (MM) method. Then, a block coordinate descent (BCD) method is proposed to obtain a suboptimal solution, where the precoding matrices and the phase shifters are alternately optimized. Specifically, the digital precoding matrix design problem is solved by the quadratically constrained quadratic programming (QCQP), while the analog phase shift optimization is solved by the Riemannian manifold optimization (RMO). The convergence and computational complexity are analyzed. Finally, simulation results are provided to verify the performance of the proposed design, as well as the effectiveness of double-IRS in improving the spectral efficiency
Interplay of Spin-Orbit Interactions, Dimensionality, and Octahedral Rotations in Semimetallic SrIrO
We employ reactive molecular-beam epitaxy to synthesize the metastable
perovskite SrIrO and utilize {\it in situ} angle-resolved photoemission
to reveal its electronic structure as an exotic narrow-band semimetal. We
discover remarkably narrow bands which originate from a confluence of strong
spin-orbit interactions, dimensionality, and both in- and out-of-plane IrO
octahedral rotations. The partial occupation of numerous bands with strongly
mixed orbital characters signals the breakdown of the single-band Mott picture
that characterizes its insulating two-dimensional counterpart,
SrIrO, illustrating the power of structure-property relations for
manipulating the subtle balance between spin-orbit interactions and
electron-electron interactions
SDSS-IV MANGA: Spatially Resolved Star Formation Main Sequence and LI(N)ER Sequence
We present our study on the spatially resolved H_alpha and M_star relation
for 536 star-forming and 424 quiescent galaxies taken from the MaNGA survey. We
show that the star formation rate surface density (Sigma_SFR), derived based on
the H_alpha emissions, is strongly correlated with the M_star surface density
(Sigma_star) on kpc scales for star- forming galaxies and can be directly
connected to the global star-forming sequence. This suggests that the global
main sequence may be a consequence of a more fundamental relation on small
scales. On the other hand, our result suggests that about 20% of quiescent
galaxies in our sample still have star formation activities in the outer region
with lower SSFR than typical star-forming galaxies. Meanwhile, we also find a
tight correlation between Sigma_H_alpha and Sigma_star for LI(N)ER regions,
named the resolved "LI(N)ER" sequence, in quiescent galaxies, which is
consistent with the scenario that LI(N)ER emissions are primarily powered by
the hot, evolved stars as suggested in the literature.Comment: 6 pages, 4 figures. ApJ Letter accepte
Giant Planar Hall Effect in Epitaxial (Ga,Mn)As Devices
Large Hall resistance jumps are observed in microdevices patterned from
epitaxial (Ga,Mn)As layers when subjected to a swept, in-plane magnetic field.
This giant planar Hall effect is four orders of magnitude greater than
previously observed in metallic ferromagnets. This enables extremely sensitive
measurements of the angle-dependent magnetic properties of (Ga,Mn)As. The
magnetic anisotropy fields deduced from these measurements are compared with
theoretical predictions.Comment: 3 figure
Efficient Multi-Party Quantum Secret Sharing Schemes
In this work, we generalize the quantum secret sharing scheme of Hillary,
Bu\v{z}ek and Berthiaume[Phys. Rev. A59, 1829(1999)] into arbitrary
multi-parties. Explicit expressions for the shared secret bit is given. It is
shown that in the Hillery-Bu\v{z}ek-Berthiaume quantum secret sharing scheme
the secret information is shared in the parity of binary strings formed by the
measured outcomes of the participants. In addition, we have increased the
efficiency of the quantum secret sharing scheme by generalizing two techniques
from quantum key distribution. The favored-measuring-basis Quantum secret
sharing scheme is developed from the Lo-Chau-Ardehali technique[H. K. Lo, H. F.
Chau and M. Ardehali, quant-ph/0011056] where all the participants choose their
measuring-basis asymmetrically, and the measuring-basis-encrypted Quantum
secret sharing scheme is developed from the Hwang-Koh-Han technique [W. Y.
Hwang, I. G. Koh and Y. D. Han, Phys. Lett. A244, 489 (1998)] where all
participants choose their measuring-basis according to a control key. Both
schemes are asymptotically 100% in efficiency, hence nearly all the GHZ-states
in a quantum secret sharing process are used to generate shared secret
information.Comment: 7 page
A Concentration/Purification Scheme for Two Partially Entangled Photon Pairs
An experimental scheme for concentrating entanglement in partially entangled
photon pairs is proposed. In this scheme, two separated parties obtain one
maximally entangled photon pair from previously shared two partially entangled
photon pairs by local operations and classical communication. A practical
realization of the proposed scheme is discussed, which uses imperfect photon
detectors and spontaneous parametric down-conversion as a photon source. This
scheme also works for purifying a class of mixed states.Comment: 8 pages, 3 figure
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