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<jats:p>Graphene and transition metal dichalcogenides (TMDs), two-dimensional materials, have been investigated wildely in recent years. As a member of the TMD family, MoTe<jats:sub>2</jats:sub> possesses a suitable bandgap of ∼ 1.0 eV for near infrared (NIR) photodetection. Here we stack the MoTe<jats:sub>2</jats:sub> flake with two graphene flakes of high carrier mobility to form a graphene–MoTe<jats:sub>2</jats:sub>–graphene heterostructure. It exhibits high photo-response to a broad spectrum range from 500 nm to 1300 nm. The photoresponsivity is calculated to be 1.6 A/W for the 750-nm light under 2 V/0 V drain–source/gate bias, and 154 mA/W for the 1100-nm light under 0.5 V/60 V drain–source/gate bias. Besides, the polarity of the photocurrent under zero <jats:italic>V</jats:italic> <jats:sub>ds</jats:sub> can be efficiently tuned by the back gate voltage to satisfy different applications. Finally, we fabricate a vertical graphene–MoTe<jats:sub>2</jats:sub>–graphene heterostructure which shows improved photoresponsivity of 3.3 A/W to visible light.</jats:p>

<jats:p>As an important member of the two-dimensional layers of metal dichalcogenides family, the two-dimensional (2D) group IV metal chalcogenides (GIVMCs) have been attracting intensive attention. However, the growth of monolayer tin disulfide (SnS<jats:sub>2</jats:sub>) remains a great challenge contrasted to transition metal dichalcogenides, which have been studied quite maturely. Till date, there have been scant reports on the growth of large-scale and large-size monolayer SnS<jats:sub>2</jats:sub>. Here, we successfully synthesized monolayer SnS<jats:sub>2</jats:sub> crystal on SiO<jats:sub>2</jats:sub>/Si substrates via NaCl-assisted CVD and the edge can be as long as 80 μm. Optical microscope, Raman spectroscopy, x-ray diffraction, atomic force microscopy (AFM), and energy-dispersion x-ray (EDX) were performed respectively to investigate the morphology, crystallographic structure, and optical property of the 2D SnS<jats:sub>2</jats:sub> nanosheets. In addition, we discussed the growing mechanism of the NaCl-assisted CVD method.</jats:p>

<jats:p>This study presents a systematic review of the literature pertaining to dye-sensitized solar cells (DSSCs), in order to anticipate the direction and speed of change in technology trend. To study the general progression in DSSC research, we have assessed the evolution in annual DSSCs publications and their citations. Further, in order to identify the intellectual bases, we have also classified the journals, authors, institutes, and countries according to their scientific productivity in the field of DSSCs research during the period of 2007–2017.</jats:p>

<jats:p>We report properties of contact resistances observed on pentacene organic field-effect transistors (OFET) with four different source/drain electrodes, namely, copper (Cu), gold (Au), silver (Ag), and germanium (Ge). The metals were selected to provide a wide range of energy barriers for charge injection, from blocking contact to smooth injection. All OFETs exhibited strong voltage dependence of the contact resistance, even for devices with smooth injection, which is in strong disagreement with the definition of ohmic contacts. A comparison with current crowding, resistive network, Fowler–Nordheim tunneling, and electric field enhanced thermionic injection (Schottky emission) pointed to importance of local electric fields and/or electrostatic field charges.</jats:p>

<jats:p>A type of photonic crystal fiber based on Kagome lattice cladding and slot air holes in a rectangular core is investigated. Full vector finite element method is used to evaluate the modal and propagation properties of the designed fiber. High birefringence of 0.089 and low effective material loss of 0.055 cm<jats:sup>−1</jats:sup> are obtained at 1 THz. The <jats:italic>y</jats:italic>-polarized fundamental mode of the designed fiber shows a flattened and near-zero dispersion of 0 ± 0.45 ps · THz<jats:sup>−1</jats:sup> · cm<jats:sup>−1</jats:sup> within a broad frequency range (0.5 THz–1.5 THz). Our results provide the theory basis for applications of the designed fiber in terahertz polarization maintaining systems.</jats:p>

<jats:p>Based on the hybrid solutions to (2+1)-dimensional Kadomtsev–Petviashvili (KP) equation, the motion trajectory of the solutions to KP equation is further studied. We obtain trajectory equation of a single lump before and after collision with line, lump, and breather waves by approximating solutions of KP equation along some parallel orbits at infinity. We derive the mathematical expression of the phase change before and after the collision of a lump wave. At the same time, we give some collision plots to reveal the obvious phase change. Our method proposed to find the trajectory equation of a lump wave can be applied to other (2+1)-dimensional integrable equations. The results expand the understanding of lump, breather, and hybrid solutions in soliton theory.</jats:p>

<jats:p>To transform the exponential traveling wave solutions to bilinear differential equations, a sufficient and necessary condition is proposed. Motivated by the condition, we extend the results to the (2+1)-dimensional Kadomtsev–Petviashvili (KP) equation, the (3+1)-dimensional generalized Kadomtsev–Petviashvili (g-KP) equation, and the B-type Kadomtsev–Petviashvili (BKP) equation. Aa a result, we obtain some new resonant multiple wave solutions through the parameterization for wave numbers and frequencies via some linear combinations of exponential traveling waves. Finally, these new resonant type solutions can be displayed in graphs to illustrate the resonant behaviors of multiple wave solutions.</jats:p>

<jats:p>The dynamical behavior of a photon-added thermal state (PATS) in a thermal reservoir is investigated by virtue of Wigner function (WF) and Wigner logarithmic negativity (WLN), where this propagation model is abstracted as an input–output problem in a thermal-loss channel. The density operator of the output optical field at arbitrary time can be expressed in the integration form of the characteristics function of the input optical field. The exact analytical expression of WF is given, which is closely related to the Laguerre polynomial and is dependent on the evolution time and other interaction parameters (related with the initial field and the reservoir). Based on the WLN, we observe the dynamical evolution of the PATS in the thermal reservoir. It is shown that the thermal noise will make the PATS lose the non-Gaussianity.</jats:p>

<jats:p>There are some problems that quantum computers seem to be exponentially faster than classical computers, like factoring large numbers, machine learning, and simulation of quantum systems. Constructing an appropriate quantum algorithm becomes more important for solving these specific problems. In principle, any quantum algorithm can recast by a quantum random walk algorithm. Although quantum random walk with a few qubits has been implemented in a variety of systems, the experimental demonstration of solid-state quantum random walk remains elusive. Here we report the experimental implementation of the quantum continuous-time random walk algorithm by a two-qubit quantum processor in a nitrogen–vacancy center in diamond. We found that quantum random walk on a circle does not converge to any stationary distribution and exhibit a reversible property. Our results represent a further investigation of quantum walking dynamics in solid spin platforms, may also lead to other practical applications by the use of quantum continuous-time random walk for quantum algorithm design and quantum coherence transport.</jats:p>

<jats:p>We report a fabrication process and characterization of the Josephson parametric amplifier (JPA) for the single-shot quantum state measurement of superconducting multiqubit system. The device is prepared using Nb film as its base layer, which is convenient in the sample patterning process like e-beam lithography and film etching. Our results show that the JPA has a bandwidth up to 600 MHz with gain above 15 dB and noise temperature approaching the quantum limit. The qubit state differentiation measurements demonstrate the signal-to-noise ratio around 3 and the readout fidelity above 97% and 91% for the ground and first-excited states, respectively.</jats:p>