Catálogo de publicaciones - revistas

<jats:p>The morphology and interface of perovskite film are very important for the performance of perovskite solar cells (PSCs). The quality of perovskite film, fabricated via two-step spin-coating process, is significantly influenced by the morphology and crystallinity of PbI<jats:sub>2</jats:sub> film. With the addition of additive dimethyl sulfoxide (DMSO) into the PbI<jats:sub>2</jats:sub> precursor, the roughness and trap-state density of perovskite film have been significantly reduced, leading to the excellent contact between perovskite layer and subsequent deposited carrier transport layer. Accordingly, the planar heterojunction PSCs with an architecture of ITO/SnO<jats:sub>2</jats:sub>/perovskite/PTAA/Ag show an efficiency up to 19.02%. Furthermore, PSCs exhibit promising stability in air with a humidity of ∼ 45%, and retain 80% of initial efficiency after being exposed to air for 400 h without any encapsulation.</jats:p>

<jats:p>It is generally accepted that herding behavior and overconfidence behavior are unrelated or even mutually exclusive. However, these behaviors can both lead to some similar market anomalies, such as excessive trading volume and volatility in the stock market. Due to the limitation of traditional time series analysis, we try to study whether there exists network relevance between the investor’s herding behavior and overconfidence behavior based on the complex network method. Since the investor’s herding behavior is based on market trends and overconfidence behavior is based on past performance, we convert the time series data of market trends into a market network and the time series data of the investor’s past judgments into an investor network. Then, we update these networks as new information arrives at the market and show the weighted in-degrees of the nodes in the market network and the investor network can represent the herding degree and the confidence degree of the investor, respectively. Using stock transaction data of Microsoft, US S&amp;P 500 stock index, and China Hushen 300 stock index, we update the two networks and find that there exists a high similarity of network topological properties and a significant correlation of node parameter sequences between the market network and the investor network. Finally, we theoretically derive and conclude that the investor’s herding degree and confidence degree are highly related to each other when there is a clear market trend.</jats:p>

<jats:p>In complex networks, identifying influential spreader is of great significance for improving the reliability of networks and ensuring the safe and effective operation of networks. Nowadays, it is widely used in power networks, aviation networks, computer networks, and social networks, and so on. Traditional centrality methods mainly include degree centrality, closeness centrality, betweenness centrality, eigenvector centrality, <jats:italic>k</jats:italic>-shell, <jats:italic>etc</jats:italic>. However, single centrality method is one-sided and inaccurate, and sometimes many nodes have the same centrality value, namely the same ranking result, which makes it difficult to distinguish between nodes. According to several classical methods of identifying influential nodes, in this paper we propose a novel method that is more full-scaled and universally applicable. Taken into account in this method are several aspects of node’s properties, including local topological characteristics, central location of nodes, propagation characteristics, and properties of neighbor nodes. In view of the idea of the multi-attribute decision-making, we regard the basic centrality method as node’s attribute and use the entropy weight method to weigh different attributes, and obtain node’s combined centrality. Then, the combined centrality is applied to the gravity law to comprehensively identify influential nodes in networks. Finally, the classical susceptible-infected-recovered (SIR) model is used to simulate the epidemic spreading in six real-society networks. Our proposed method not only considers the four topological properties of nodes, but also emphasizes the influence of neighbor nodes from the aspect of gravity. It is proved that the new method can effectively overcome the disadvantages of single centrality method and increase the accuracy of identifying influential nodes, which is of great significance for monitoring and controlling the complex networks.</jats:p>

<jats:p>With the aid of Lenard recursion equations, an integrable hierarchy of nonlinear evolution equations associated with a 2 × 2 matrix spectral problem is proposed, in which the first nontrivial member in the positive flows can be reduced to a new generalization of the Wadati–Konno–Ichikawa (WKI) equation. Further, a new generalization of the Fokas–Lenells (FL) equation is derived from the negative flows. Resorting to these two Lax pairs and Riccati-type equations, the infinite conservation laws of these two corresponding equations are obtained.</jats:p>

<jats:p>A scheme is proposed to generate genuine tripartite Einstein–Podolsky–Rosen (EPR) steering in cascaded nonlinear process of the fourth-harmonic generation. The second-harmonic is generated by the first double-frequency process in an optical superlattice. Then, the fourth-harmonic is produced by the second cascaded double-frequency process through quasi-phase-matching technique in the same optical superlattice. The genuine tripartite EPR steering among the pump, the second-harmonic, and the fourth-harmonic beams can be obtained by this cascaded nonlinear process according to a criterion for genuine multipartite quantum steering. The quantum steering properties are discussed by adjusting the parameters related to the cascaded nonlinear system. The present research provides a reference scheme and data for obtaining good multipartite EPR steering in experiment and can advance the applications of quantum steering in the quantum information processing.</jats:p>

<jats:p>The classical version of Mandelstam–Tamm speed limit based on the Wigner function in phase space was reported by Shanahan <jats:italic>et al.</jats:italic> [<jats:italic>Phys. Rev. Lett.</jats:italic> <jats:bold>120</jats:bold> 070401 (2018)]. We present the Margolus–Levitin speed limit across the quantum-to-classical transition in phase space based on the trace distance. The Margolus–Levitin speed limit is set by the Schatten <jats:italic>L</jats:italic> <jats:sub>1</jats:sub> norm of the generator of time-dependent evolution for both the quantum and classical domains. As an example, the time-dependent harmonic oscillator is considered to illustrate the result.</jats:p>

<jats:p>By using the parameter differential method of operators, we recast the combination function of coordinate and momentum operators into its normal and anti-normal orderings, which is more ecumenical, simpler, and neater than the existing ways. These products are very useful in obtaining some new differential relations and useful mathematical integral formulas. Further, we derive the normally ordered form of the operator (<jats:italic>fQ</jats:italic> + <jats:italic>gP</jats:italic>)<jats:sup>−<jats:italic>n</jats:italic> </jats:sup> with <jats:italic>n</jats:italic> being an arbitrary positive integer by using the parameter tracing method of operators together with the intermediate coordinate–momentum representation. In addition, general mutual transformation rules of the normal and anti-normal orderings, which have good universality, are derived and hence the anti-normal ordering of (<jats:italic>fQ</jats:italic> + <jats:italic>gP</jats:italic>)<jats:sup>−<jats:italic>n</jats:italic> </jats:sup> is also obtained. Finally, the application of some new identities is given.</jats:p>

<jats:p>We propose a scheme to generate entanglement between two distant qubits (two-level atom) which are separately trapped in their own (in general) non-Markovian dissipative cavities by utilizing entangling swapping, considering the case in which the qubits can move along their cavity axes rather than a static state of motion. We first examine the role of movement of the qubit by studying the entropy evolution for each subsystem. The average entropy over the initial states of the qubit is calculated. Then by performing a Bell state measurement on the fields leaving the cavities, we swap the entanglement between qubit-field in each cavity into qubit-qubit and field-field subsystems. The entangling power is used to measure the average amount of swapped entanglement over all possible pure initial states. Our results are presented in two weak and strong coupling regimes, illustrating the positive role of movement of the qubits on the swapped entanglement. It is revealed that by considering certain conditions for the initial state of qubits, it is possible to achieve a maximally long-leaving stationary entanglement (Bell state) which is entirely independent of the environmental variables as well as the velocity of qubits. This happens when the two qubits have the same velocities.</jats:p>

<jats:p>Quantum full adders play a key role in the design of quantum computers. The efficiency of a quantum adder directly determines the speed of the quantum computer, and its complexity is closely related to the difficulty and the cost of building a quantum computer. The existed full adder based on R gate is a great design but it is not suitable to construct a quantum multiplier. We show the quantum legitimacy of some common reversible gates, then use R gate to propose a new design of a quantum full adder. We utilize the new designed quantum full adder to optimize the quantum multiplier which is based on R gate. It is shown that the new designed one can be optimized by a local optimization rule so that it will have lower quantum cost than before.</jats:p>

<jats:p>We propose schemes to realize quantum state transfer and prepare quantum entanglement in coupled cavity and cavity–fiber–cavity systems, respectively, by using the dressed state method. We first give the expression of pulses shape by using dressed states and then find a group of Gaussian pulses that are easy to realize in experiment to replace the ideal pulses by curve fitting. We also study the influence of some parameters fluctuation, atomic spontaneous emission, and photon leakage on fidelity. The results show that our schemes have good robustness. Because the atoms are trapped in different cavities, it is easy to perform different operations on different atoms. The proposed schemes have the potential applications in dressed states for distributed quantum information processing tasks.</jats:p>