Catálogo de publicaciones - revistas

<jats:p>Living systems are full of astonishing diversity and complexity of life. Despite differences in the length scales and cognitive abilities of these systems, collective motion of large groups of individuals can emerge. It is of great importance to seek for the fundamental principles of collective motion, such as phase transitions and their natures. Via an eigen microstate approach, we have found a discontinuous transition of density and a continuous transition of velocity in the Vicsek models of collective motion, which are identified by the finite-size scaling form of order-parameter. At strong noise, living systems behave like gas. With the decrease of noise, the interactions between the particles of a living system become stronger and make them come closer. The living system experiences then a discontinuous gas–liquid like transition of density. The even stronger interactions at smaller noise make the velocity directions of the particles become ordered and there is a continuous phase transition of collective motion in addition.</jats:p>

<jats:p>In a certain period, some news will compete for the top news to gain the most attention and influence, and more news will be submerged in the ocean of news and become mediocre. This article deeply studies the evolution process and competition mechanism of the dissemination of Weibo news. In this paper, we innovatively propose a pre-processing scheme for traditional small–world networks and scale–free networks and divide nodes into three roles: fans, passersby, and anti-fans. The competition mechanism of Weibo top news is defined from the aspects of node role and node aggregation degree. A network evolution model is established based on the competition mechanism. The propagation characteristics of the network evolution model are deeply analyzed, and simulation experiments are performed on the small–world network and the scale–free network. Finally, the validity and rationality of the new model are verified through comparative experiments, and a feasible scheme for the propagation of top news onWeibo is given.</jats:p>

<jats:p>The proton distribution in inner radiation belt is often affected by strong geomagnetic storm disturbance. Based on the data of the sun-synchronous CSES satellite, which carries with several high energy particle payloads and was launched in February 2018, we analyzed the extensive proton variations in the inner radiation belt in a wide energy range of 2 MeV– 220 MeV during 2018 major geomagnetic storm. The result indicates that the loss mechanism of protons was energy dependence which is consistent with some previous studies. For protons at low energy 2 MeV–20 MeV, the fluxes were decreased during main phase of the storm and did not come back quickly during the recovery phase, which is likely to be caused by Coulomb collision due to neutral atmosphere density variation. At higher energy 30 MeV–100 MeV, it was confirmed that the magnetic field line curvature scattering plays a significant role in the proton loss phenomenon during this storm. At highest energies &gt; 100 MeV, the fluxes of protons kept a stable level and did not exhibit a significant loss during this storm.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>This paper introduces a new approach for the determination of the source region of BW (beat wave) modulation. This type of modulation is achieved by transmitting HF continuous waves with a frequency difference of <jats:italic>f</jats:italic>, where <jats:italic>f</jats:italic> is the frequency of modulated ELF/VLF (extremely low frequency/very low frequency) waves from two sub-arrays of a high power HF transmitter. Despite the advantages of BW modulation in terms of generating more stable ELF/VLF signal and high modulation efficiency, there exists a controversy on the physical mechanism of BW and its source region. In this paper, the two controversial theories, i.e. BW based on D-E region thermal nonlinearity and BW based on F region ponderomotive nonlinearity are examined for cases where each of these two theories exists exclusively or both of them exist simultaneously. According to the analysis and the simulation results presented in this paper, it is found that the generated VLF signal amplitude exhibits significant variation as a function of HF frequency in different source regions. Therefore, this characteristic can be utilised as a potential new approach to determine the physical mechanism and source location of BW.</jats:p>

<jats:p>We report theoretical studies of electron impact triple differential cross sections of two bio-molecules, pyrimidine and tetrahydrofurfuryl alcohol, in the coplanar asymmetric kinematic conditions with the impact energy of 250 eV and ejected electron energy of 20 eV at three scattering angles of −5°, −10°, and −15°. Present multi-center distorted-wave method well describes the experimental data, which was obtained by performing (e, 2e) experiment. The calculations show that the secondary electron produced by the primary impact electron is strongly influenced by the molecular ionic multi-center potential, which must be considered when the low energy electron interacts with DNA analogues.</jats:p>

<jats:p>The protection of the entanglement between two V-atoms (EBTVA) in a multi-cavity coupling system is studied. The whole system consists of two V-atoms. The two V-atoms are initially in the maximum entangled state and interacts locally with its own dissipative cavity which is coupled to the external cavities with high quality factor (ECWHQF). The results show that, when there is no ECWHQF, the EBTVA can be protected effectively in the case where the V-atom and the dissipative cavity are weak coupled in large detuning, while when there are different numbers <jats:italic>n</jats:italic> of ECWHQF coupled to two dissipative cavities, by adjusting the parameters of the number <jats:italic>n</jats:italic> of ECWHQF and the coupling strength <jats:italic>k</jats:italic> between cavities, the EBTVA can be protected perfectly and continuously. Our result provides an effective method for protecting entanglement resources of three-level system.</jats:p>

<jats:p>A novel efficient semi-quantum private comparison protocol based on the d-dimensional GHZ states is proposed. With the assistance of semi-honest third party, two classical participants can compare the size relation of their secretswithout any information leakage. To reduce the consumption of quantum devices, the qubit efficiency of our protocol isimproved by introducing the semi-quantum conception via the existing semi-quantum privatecomparisons. Furthermore,it is unnecessary to prepare the secure classical authentication channel among participants in advance. It is shown that our protocol is not only correct and efficient, but also free from external and internal attacks.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Quantum error-correction codes are immeasurable resources for quantum computing and quantum communication. However, the existing decoders are generally incapable of checking node duplication of belief propagation (BP) on quantum low-density parity check (QLDPC) codes. Based on the probability theory in the machine learning, mathematical statistics and topological structure, a GF(4) (the Galois field is abbreviated as GF) augmented model BP decoder with Tanner graph is designed. The problem of repeated check nodes can be solved by this decoder. In simulation, when the random perturbation strength <jats:italic>p</jats:italic>=0.0115–0.0116 and number of attempts <jats:italic>N</jats:italic> = 60–70, the highest decoding efficiency of the augmented model BP decoder is obtained, and the low-loss frame error rate (FER) decreases to 7.1975 ×10<jats:sup>−5</jats:sup>. Hence, we design a novel augmented model decoder to compare the relationship between GF(2) and GF(4) for quantum code [[450,200]] on the depolarization channel. It can be verified that the proposed decoder provides the widely application range, and the decoding performance is better in QLDPC codes.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We propose a scheme where one can exploit auxiliary resources to achieve quantum multicast communication with network coding over the butterfly network. In this paper, we propose the quantum 2-pair multicast communication scheme, and extend it to <jats:italic>k</jats:italic>-pair multicast communication over the extended butterfly network. Firstly, an EPR pair is shared between each adjacent node on the butterfly network, and make use of local operation and classical communication to generate entangled relationship between non-adjacent nodes. Secondly, each sender adds auxiliary particles according to the multicast number <jats:italic>k</jats:italic>, in which the CNOT operations are applied to form the multi-particle entangled state. Finally, combined with network coding and free classical communication, quantum multicast communication based on quantum measurements is completed over the extended butterfly network. Not only the bottleneck problem is solved, but also quantum multicast communication can be completed in our scheme. At the same time, regardless of multicast number <jats:italic>k</jats:italic>, the maximum capacity of classical channel is 2 bits, and quantum channel is used only once.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We propose a lumped element Josephson parametric amplifier with vacuum-gap-based capacitor. The capacitor is made of quasi-floating aluminum pad and on-chip ground. We take a fabrication process compatible with air-bridge technology, which makes our design adaptable for future on-chip integrated quantum computing system. Further engineering the input impedance, we obtain a gain above 20 dB over 162-MHz bandwidth, along with a quasi quantum-limit noise performance. This work should facilitate the development of quantum information processing and integrated superconducting circuit design.</jats:p>