d'Alembert-Schrödinger hybrid simulation for laser-induced multiquantum state transitions in a three-dimensional artificial atom.

In this Letter, a d'Alembert-Schrödinger hybrid method is proposed to analyze the transient interaction between the incident electromagnetic control pulse and the electron. This hybrid method is based on the d'Alembert equation, which describes the propagation of the electromagnetic field and the time-dependent Schrödinger equation, which describes the action of the electron. Moreover, the finite-difference time-domain method is used to solve those equations. In our simulation, using the presented hybrid equations and the control equation of the quantum state, a scheme is presented to design laser pulses to control discrete quantum states in a three-dimensional artificial atom model. Excitingly, the laser pulses have been successfully designed for the perfect four quantum states' transition for the first time. With that, the spatiotemporal distribution for the probability density of an electron wave packet is showed in detail to describe the laser-induced transition process of quantum states.

Tuning electronic and optical properties of arsenene/C3N van der Waals heterostructure by vertical strain and external electric field.

Searching for new van der Waals (vdW) heterostructure with novel electronic and optical properties is of great interest and importance for the next generation of devices. By using first-principles calculations, we show that the electronic and optical properties of the arsenene/C3N vdW heterostructure can be effectively modulated by applying vertical strain and external electric field. Our results suggest that this heterostructure has an intrinsic type-II band alignment with an indirect bandgap of 0.16 eV, facilitating the separation of photogenerated electron-hole pairs. The bandgap in the heterostructure can be tuned from 0-0.35 eV via the strain, experiencing an indirect-to-direct bandgap transition. Moreover, the bandgap of the heterostructure varies linearly with respect to a moderate external electric field, and the semiconductor-to-metal transition can be realized in the presence of a strong electric field. The calculated band alignment and the optical absorption reveal that the arsenene/C3N heterostructure could present excellent light-harvesting performance. Our designed vdW heterostructure is expected to have great potential applications in nanoelectronic devices and photovoltaics.

Monolayered Silicon and Germanium Monopnictide Semiconductors: Excellent Stability, High Absorbance, and Strain Engineering of Electronic Properties.

The discovery of stable two-dimensional (2D) semiconductors with exotic electronic properties is crucial to the future electronic technologies. Using the first-principles calculations, we predict the monolayered Silicon- and Germanium-monopnictides as a new class of semiconductors owning excellent dynamical and thermal stabilities, prominent anisotropy, and high possibility of experimental exfoliation. These semiconductors, including the monolayered SiP, SiAs, GeP, and GeAs, possess wide bandgaps of 2.08-2.64 eV obtained by hybrid functional calculation. Under small uniaxial strains (-2 to 3%), dramatic modulations of their band structures are observed, and furthermore, all the 2D monolayers (MLs) can be transformed between indirect and direct semiconductors. The monolayered GeAs and SiP exhibits extraordinary optical absorption in the range of visible and ultraviolet (UV) light spectra, respectively. The exfoliation energies of these monolayers are comparable to graphene, implying a strong probability of successful fabrication by mechanical exfoliation. These intriguing properties of the monolayered silicon- and germanium-monopnictides, combined with their highly stable structures, offer tremendous opportunities for electronic and optoelectronic devices working under UV-visible spectrum.