4,132 research outputs found
Multipartite entanglement purification with quantum nondemolition detectors
We present a scheme for multipartite entanglement purification of quantum
systems in a Greenberger-Horne-Zeilinger state with quantum nondemolition
detectors (QNDs). This scheme does not require the controlled-not gates which
cannot be implemented perfectly with linear optical elements at present, but
QNDs based on cross-Kerr nonlinearities. It works with two steps, i.e., the
bit-flipping error correction and the phase-flipping error correction. These
two steps can be iterated perfectly with parity checks and simple single-photon
measurements. This scheme does not require the parties to possess sophisticated
single photon detectors. These features maybe make this scheme more efficient
and feasible than others in practical applications.Comment: 8 pages, 5 figure
Improving the security of multiparty quantum secret sharing against Trojan horse attack
We analyzed the security of the multiparty quantum secret sharing (MQSS)
protocol recently proposed by Zhang, Li and Man [Phys. Rev. A \textbf{71},
044301 (2005)] and found that this protocol is secure for any other
eavesdropper except for the agent Bob who prepares the quantum signals as he
can attack the quantum communication with a Trojan horse. That is, Bob replaces
the single-photon signal with a multi-photon one and the other agent Charlie
cannot find this cheating as she does not measure the photons before they runs
back from the boss Alice, which reveals that this MQSS protocol is not secure
for Bob. Finally, we present a possible improvement of the MQSS protocol
security with two single-photon measurements and six unitary operations.Comment: 4 pages, 2 figures; The revised version of the paper published in
Phys. Rev. A 72, 044302 (2005). A bug is modified and an addendum is adde
A Deep Decomposition Network for Image Processing: A Case Study for Visible and Infrared Image Fusion
Image decomposition is a crucial subject in the field of image processing. It
can extract salient features from the source image. We propose a new image
decomposition method based on convolutional neural network. This method can be
applied to many image processing tasks. In this paper, we apply the image
decomposition network to the image fusion task. We input infrared image and
visible light image and decompose them into three high-frequency feature images
and a low-frequency feature image respectively. The two sets of feature images
are fused using a specific fusion strategy to obtain fusion feature images.
Finally, the feature images are reconstructed to obtain the fused image.
Compared with the state-of-the-art fusion methods, this method has achieved
better performance in both subjective and objective evaluation
Revisiting mixing in QCD sum rules
We investigate the mixing caused by the flavor
symmetry breaking. The mixing angle is expressed by a matrix
element induced by the operators that breaks flavor symmetry. The QCD
contribution to this matrix element is assumed to be dominated and calculated
by QCD sum rules. A three-point correlation function is defined and handled
both at the hadron and quark-gluon levels. The quark-gluon level calculation is
based on operator product expansion up to dimension-5 condensates. A detailed
numerical analysis is performed to determine the Borel parameters, and the
obtained mixing angle is or
.Comment: 14 pages, 7 figures and 1 tabl
Increased electrical conductivity in fine-grained (Zr,Hf)NiSn based thermoelectric materials with nanoscale precipitates
Grain refinement has been conducted to reduce the thermal conductivity and improve the thermoelectric performance of the (Zr,Hf)NiSn based half-Heusler alloys. Nanoscale in situ
precipitates were found embedded in the matrix with submicron grains. The lattice thermal conductivity was decreased due to the enhanced boundary scattering of phonons. The increased carrier concentration and electrical conductivity were observed compared to the coarse-grained
alloys, which is discussed in relation to the existence of nanoscale precipitates, the effect of antisite defects, and composition change. It is suggested that the nanoscale precipitates play a significant role in the observed electrical conductivity increase
- …