Catálogo de publicaciones - revistas

<jats:p>The performance damage mechanism of InP-based high electron mobility transistors (HEMTs) after proton irradiation has been investigated comprehensively through induced defects. The effects of the defect type, defect energy level with respect to conduction band <jats:italic>E</jats:italic> <jats:sub>T</jats:sub>, and defect concentration on the transfer and output characteristics of the device are discussed based on hydrodynamic model and Shockley–Read–Hall recombination model. The results indicate that only acceptor-like defects have a significant influence on device operation. Meanwhile, as defect energy level <jats:italic>E</jats:italic> <jats:sub>T</jats:sub> shifts away from conduction band, the drain current decreases gradually and finally reaches a saturation value with <jats:italic>E</jats:italic> <jats:sub>T</jats:sub> above 0.5 eV. This can be attributed to the fact that at sufficient deep level, acceptor-type defects could not be ionized any more. Additionally, the drain current and transconductance degrade more severely with larger acceptor concentration. These changes of the electrical characteristics with proton radiation could be accounted for by the electron density reduction in the channel region from induced acceptor-like defects.</jats:p>

<jats:p>Superconducting nanowire single-photon detectors (SNSPDs) have attracted considerable attention owing to their excellent detection performance; however, the underlying physics of the detection process is still unclear. In this study, we investigate the wavelength dependence of the intrinsic detection efficiency (IDE) for NbN SNSPDs. We fabricate various NbN SNSPDs with linewidths ranging from 30 nm to 140 nm. Then, for each detector, the IDE curves as a function of bias current for different incident photon wavelengths of 510–1700 nm are obtained. From the IDE curves, the relations between photon energy and bias current at a certain IDE are extracted. The results exhibit clear nonlinear energy–current relations for the NbN detectors, indicating that a detection model only considering quasiparticle diffusion is unsuitable for the meander-type NbN-based SNSPDs. Our work provides additional experimental data on SNSPD detection mechanism and may serve as an interesting reference for further investigation.</jats:p>

<jats:p>The topological magnon insulator on a honeycomb lattice with Dzyaloshinskii–Moriya interaction (DMI) is studied under the application of a circularly polarized light. At the high-frequency regime, the effective tight-binding model is obtained based on Brillouin–Wigner theory. Then, we study the corresponding Berry curvature and Chern number. In the Dirac model, the interplay between a light-induced handedness-dependent effective DMI and intrinsic DMI is discussed.</jats:p>

<jats:p>Metal ions play critical roles in the interaction between deoxyribonucleic acid (DNA) and protein. The experimental research has demonstrated that the Mg<jats:sup>2+</jats:sup> ion can affect the binding between transcription factor and DNA. In our work, by full-atom molecular dynamic simulation, the effects of the Mg<jats:sup>2+</jats:sup> ion on the cyclic adenosine monophosphate (cAMP) response element binding protein (CREB)/cAMP response elements (CRE) complex are investigated. It is illustrated that the number of hydrogen bonds formed at the interface between protein and DNA is significantly increased when the Mg<jats:sup>2+</jats:sup> ion is added. Hence, an obvious change in the structure of the DNA is observed. Then the DNA base groove and base pair parameters are analyzed. We find that, due to the introduction of the Mg<jats:sup>2+</jats:sup> ion, the DNA base major groove becomes narrower. A potential mechanism for this observation is proposed. It is confirmed that the Mg<jats:sup>2+</jats:sup> ion can enhance the stability of the DNA–protein complex.</jats:p>

<jats:p>The emergence of cooperation still remains a fundamental conundrum in the social and behavior sciences. We introduce a new mechanism, deposit mechanism, into theoretical model to explore how this mechanism promotes cooperation in a well-mixed population. Firstly, we extend the common binary-strategy combination of cooperation and defection in public good game by adding a third strategy, namely, deposit cooperation. The players with deposit cooperation strategy pay a deposit in advance to obtain the benefits of public good at a lower contributions compared with the players with cooperation strategy, when the provision of public good is successful. Then, we explore the evolution of cooperation in the public good game with deposit by means of the replicator dynamics. Theoretical computations and stimulations show that the deposit mechanism can promote cooperation in a well-mixed population, and the numbers of equilibrium point are determined by variables of public good game. On the one hand, when the coexistence of cooperators and defectors is the stable equilibrium point in the evolutionary system, increasing the threshold of public good and adopting the weak altruism way for share benefits can enhance the level of cooperation in the population. On the other hand, if the coexistence of deposit cooperators and defectors is the stable equilibrium point, it is effective to promote the deposit cooperation by lowering the values of discount and deposit, and raising the threshold of public good.</jats:p>

<jats:p>The adiabatic control is a powerful technique for many practical applications in quantum state engineering, light-driven chemical reactions and geometrical quantum computations. This paper reveals a speed limit of nonadiabatic transition in a general time-dependent parametric quantum system that leads to an upper bound function which lays down an optimal criteria for the adiabatic controls. The upper bound function of transition rate between instantaneous eigenstates of a time-dependent system is determined by the power fluctuations of the system relative to the minimum gap between the instantaneous levels. In a parametric Hilbert space, the driving power corresponds to the quantum work done by the parametric force multiplying the parametric velocity along the parametric driving path. The general two-state time-dependent models are investigated as examples to calculate the bound functions in some general driving schemes with one and two driving parameters. The calculations show that the upper bound function provides a tighter real-time estimation of nonadiabatic transition and is closely dependent on the driving frequencies and the energy gap of the system. The deviations of the real phase from Berry phase on different closed paths are induced by the nonadiabatic transitions and can be efficiently controlled by the upper bound functions. When the upper bound is adiabatically controlled, the Berry phases of the electronic spin exhibit nonlinear step-like behaviors and it is closely related to topological structures of the complicated parametric paths on Bloch sphere.</jats:p>

<jats:p>In this paper, we propose a new approach to tackle the separability problem for bipartite qudit mixed-states. This is based on the Majorana representation which allows to represent a <jats:italic>N</jats:italic>-spinors (qudit) as a symmetric state of <jats:italic>N</jats:italic> spin-1/2. We also discuss how we can exploit such representation and the notion of the biseparability of multipartite qubit states in the sense to establish new criteria of the separability problem based on the PPT and concurrence.</jats:p>

<jats:p>We present a dissipative scheme to generate an entangled steady-state between two superconducting transmon qutrits separately embedded in two coupled transmission line resonators in a circuit quantum electrodynamics (QED) setup. In our scheme, the resonant qutrit-resonator interaction and photon hopping between resonators jointly induce asymmetric energy gaps in the dressed state subspaces. The coherent driving fields induce the specific dressed state transition and the dissipative processes lead to the gradual accumulation in the population of target state, combination of both drives the system into a steady-state entanglement. Numerical simulation shows that the maximally entangled state can be produced with high fidelity and strong robustness against the cavity decay and qutrit decay, and no requirements for accurate time control. The scheme is achievable with the current experimental technologies.</jats:p>

<jats:p>Compared with the fiber channel, the atmospheric channel offers the possibility of a broader geographical coverage and more flexible transmission for continuous-variable quantum key distribution (CVQKD). However, the fluctuation of atmospheric conditions will lead to the loss of performance in atmospheric quantum communication. In this paper, we study how temperature affects atmospheric CVQKD. We mainly consider the temperature effects on the transmittance and interruption probability. From the numerical simulation analysis, it can be shown that the performance of atmospheric CVQKD is improved as temperature increases, with the other factors fixed. Moreover, the results in this work can be used to evaluate the feasibility of the experimental implementation of the atmospheric CVQKD protocols.</jats:p>