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The zero-energy variance principle can be exploited in variational quantum eigensolvers for solving general eigenstates but its capacity for obtaining a specified eigenstate, such as ground state, is limited as all eigenstates are of zero energy variance. We propose a variance-based variational quantum eigensolver for solving the ground state by searching in an enlarged space of wavefunction and Hamiltonian. With a mutual variance-Hamiltonian optimization procedure, the Hamiltonian is iteratively updated to guild the state towards to the ground state of the target Hamiltonian by minimizing the energy variance in each iteration. We demonstrate the performance and properties of the algorithm with numeral simulations. Our work suggests an avenue for utilizing guided Hamiltonian in hybrid quantum-classical algorithms.

Using the particle-in-cell simulations, we report an efficient scheme to generate a slow wave structure in the electron density of a plasma waveguide, based on the array laser–plasma interaction. The spatial distribution of the electron density of the plasma waveguide is modulated via effective control of the super-Gaussian index and array pattern code of the lasers. A complete overview of the holding time, and the bearable laser’s intensity of the electron density structure of the plasma waveguide, is obtained. In addition, the holding time of the slow wave structure of the plasma waveguide is also controlled by adjusting the frequency of the array laser beam. Finally, effects due to ion motion are discussed in detail.

Using angle-resolved photoemission spectroscopy, we study electronic structures of a Kagome metal YCr6Ge6. Band dispersions along kz direction are significant, suggesting a remarkable interlayer coupling between neighboring Kagome planes. Comparing ARPES data with first-principles calculations, we find a moderate electron correlation in this material, since band calculations must be compressed in the energy scale to reach an excellent agreement between experimental data and theoretical calculations. Moreover, as indicated by band calculations, there is a flat band in the vicinity of the Fermi level at the Γ–M–K plane in the momentum space, which could be responsible for the unusual transport behavior in YCr6Ge6.

The band structures of two-monolayer Bi(110) films on black phosphorus substrates are studied using angle-resolved photoemission spectroscopy. Within the band gap of bulk black phosphorus, the electronic states near the Fermi level are dominated by the Bi(110) film. The band dispersions revealed by our data suggest that the orientation of the Bi(110) film is aligned with the black phosphorus substrate. The electronic structures of the Bi(110) film strongly deviate from the band calculations of the free-standing Bi(110) film, suggesting that the substrate can significantly affect the electronic states in the Bi(110) film. Our data show that there are no non-trivial electronic states in Bi(110) films grown on black phosphorus substrates.

The star HE 1305-0007 is a metal-poor double-enhanced star with metallicity [Fe/H] $=-2.0$, which is just at the upper limit of the metallicity for the observed double-enhanced stars. Using a parametric model, we find that almost all s-elements were made in a single neutron exposure. This star should be a member of a post-common-envelope binary. After the s-process material has experienced only one neutron exposure in the nucleosynthesis region and is dredged-up to its envelope, the AGB evolution is terminated by the onset of common-envelope evolution. Based on the high radial-velocity of HE 1305-0007, we speculate that the star could be a runaway star from a binary system, in which the AIC event has occurred and produced the r-process elements., Comment: 4 pages, 3 figures, paper accepted for publication in Chinese Physics letters

Nucleosynthesis in advection-dominated accretion flow (ADAF) onto a black hole is proposed to be an important role in chemical evolution around compact stars. We investigate the nucleosynthesis in ADAF relevant for a black hole of low mass, different from that of the self-similar solution. In particular, the presence of supersolar metal mass fractions of some isotopes seems to be associated with the known black hole nucleosynthesis in ADAF, which offers further evidence of diversity of the chemical enrichment.

We study a laser wakefield acceleration driven by mid-infrared (mid-IR) laser pulses through two-dimensional particle-in-cell simulations. Since a mid-IR laser pulse can deliver a larger ponderomotive force as compared with the usual 0.8 μm wavelength laser pulse, it is found that electron self-injection into the wake wave occurs at an earlier time, the plasma density threshold for injection becomes lower, and the electron beam charge is substantially enhanced. Meanwhile, our study also shows that quasimonoenergetic electron beams with a narrow energy-spread can be generated by using mid-IR laser pulses. Such a mid-IR laser pulse can provide a feasible method for obtaining a high quality and high charge electron beam. Therefore, the current efforts on constructing mid-IR terawatt laser systems can greatly benefit the laser wakefield acceleration research.

A lateral current regulator diode (CRD) with field plates is proposed and experimentally demonstrated. The proposed CRD is based on the junction field-effect transistor (JFET) structure. A cathode field plate is adopted to alleviate the channel-length modulation effect and to improve the saturated I—V characteristics. An anode field plate is induced to achieve a high breakdown voltage VB of the CRD. The influence of the key device parameters on the I—V characteristics of the lateral CRD are discussed. Experimental results show that the proposed CRD presents good I—V characteristics with a high VB about 180 V and a low knee voltage (Vk) below 3 V. Furthermore, the proposed CRD has a negative temperature coefficient. The well characteristic of the proposed CRD makes it a cost-effective solution for light-emitting-diode lighting.

To extend the cluster algorithm to SU(N) × SU(N) chiral models, a variant version of Wolff's cluster algorithm is proposed and tested for the 2-dimensional SU(3) × SU(3) chiral model. The results show that the new method can reduce the critical slowing down in SU(3) × SU(3) chiral model.

The carbon-nitride thin films were deposited on the (100) oriented single-crystal KCl wafers at ambient temperatures by using rf-plasma sputtering. The IR spectrum showed that the films contained carbon-nitride bonds. The transmission electron microscopy (TEM) and x-ray diffraction (XRD) measurements indicated the existence of predicted polycrystalline β-C3N4 films on the KCl(100) wafers. And the TEM and XRD measured lattice spacings well match the calculated data.

Based on the equations of state from the relativistic mean field theory without and with the inclusion of strangeness-bearing hyperons, we study the dimensionless spin parameter j = cJ/(GM(2)) of uniformly rotating neutron stars. It is shown that the maximum value of the spin parameter j(max) of a neutron star rotating at the Keplerian frequency f(K) is j(max) similar to 0.7 when the star mass M > 0.5M(circle dot), which is sustained for various versions of equations of state without and with hyperons. The relationship between j and the scaled rotation frequency f/f(K) is found to be insensitive to the star mass or the adopted equation of state in the models without hyperons. However, the emergence of hyperons in neutron stars will lead to an uncertainty of the spin parameter j, which in turn could generate a complexity in the theoretical study of the quasi-periodic oscillations observed in disk-accreting compact-star systems.

We propose a variant version of Wolff's cluster algorithm, which may be extended to SU(N) × SU(N) chiral model, and test it in 2-dimensional SU(2) × SU(2) chiral model. The results show that the new method can efficiently reduce the critical slowing down in SU(2) × SU(2) chiral model.

The typical laser characteristics of a laser diode pumped solid-state laser with a Z-type resonator structure are analyzed by the transform circle approach. Laser waists change with the thermal focus length of the lasing medium so that the output power becomes unstable. In particular, there is a very unstable operation region when the pump power is of medium magnitude. A method is put forward to avoid this situation.

Using the new observations of several neutron-capture elements in metal-poor star HD 126238, combining a computer model and the method of least square, we accurately compute the component coefficients C1, C2, and C3. The results are C1 = 2.52, C2 = 0.26, C3 = 0.31. Then employing the values of the component coefficients, we determine the relative contributions of the r-process and the s-process to the abundances of neutron-capture elements in the HD 126238, and predict the abundances of all the neutron-capture elements in this metal-poor star. The predictions agree well with the observations.

Using Tadpole-improved lattice action, the low-lying glueball spectrum of the pure-gauge SU(2) theory is calculated on an anisotropic lattice. The results of m(0+), m(2+), and m(0-) are consistent with that for the Wilson action on much larger lattices. This shows the advantage of using the coarse, anisotropic lattice to calculate the glueball masses.

An ultralow specific on-resistance (Ron,sp) trench metal-oxide-semiconductor field effect transistor (MOSFET) with an improved off-state breakdown voltage (BV) is proposed. It features a U-shaped gate around the drift region and an oxide trench inserted in the drift region (UG MOSFET). In the on-state, the U-shaped gate induces a high density electron accumulation layer along its sidewall, which provides a low-resistance current path from the source to the drain, realizing an ultralow Ron,sp. The value of Ron,sp is almost independent of the drift doping concentration, and thus the UG MOSFET breaks through the contradiction relationship between Ron,sp and the off-state BV. Moreover, the oxide trench folds the drift region, enabling the UG MOSFET to support a high BV with a shortened cell pitch. The UG MOSFET achieves an Ron,sp of 2 mΩcm2 and an improved BV of 216 V, superior to the best existing state-of-the-art transistors at the same BV level.

In present study, the relations between the ratios of the heavy to light s-element (slow neutron capture element) abundances and the average neutron exposure are calculated for the intrinsic and extrinsic AGB stars, respectively. In addition, the inverse correlation of these ratios with metallicity is also presented and interpreted quantitatively. This work is based on the evolution of the heavy element abundances of the intrinsic AGB stars, and the calculation on the heavy element overabundances of the extrinsic AGB stars.

We find for the first time that a model Hamiltonian of s-wave superconductors in the presence of spin-orbit interactions and a Zeeman field is exactly solvable. Most intriguingly, based on the exact solutions, a novel type of Fulde—Ferrel—Larkin—Ovchinnikov ground state is rigorously revealed, in which the center-of-mass momentum of the fermion pair is proportional to the Zeeman field. We also generalize our exact analysis to the spin-orbit-coupled Bose—Einstein condensate.

We present a method of measuring the in situ superficial seafloor sound speed by using two receivers deployed vertically in sediment, based on the dispersion characteristic of normal modes in shallow water. Warping transformation is adopted to extract the first normal mode from the broadband propagation signals. Some experimental results which could validate the method are shown. One of the advantages of the method is that the seafloor sound speed can be solved directly from the relative vertical transmission loss of the first normal mode without the exact priori information of the environmental parameters such as the sound speed profile, the water-column depth and the source location.

A strained-SiGe p-channel metal-oxide-semiconductor-field-effect transistors (p-MOSFETS) with higher-κ LaLuO3 gate dielectric was fabricated and electrically characterized. The novel higher-κ (κ~30) gate dielectric, LaLuO3, was deposited by molecular-beam deposition and shows good quality for integration into the transistor. The transistor features good output and transfer characteristics. The hole mobility was extracted by the splitting C—V method and a value of 200cm2/Vs was obtained for strong inversion conditions, which indicates that the hole mobility is well enhanced by SiGe channel and that the LaLuO3 layer does not induce additional significant carrier scattering. Gate induced drain leakage is measured and analyzed by using an analytical model. Band-to-band tunneling efficiencies under high and low fields are found to be different, and the tunneling mechanism is discussed.

Short-channel high-mobility Si/Si0.5Ge0.5/silicon-on-insulator (SOI) quantum-well p-type metal-oxide-semiconductor field effect transistors (p-MOSFETs) were fabricated and electrically characterized. The transistors show good transfer and output characteristics with Ion/Ioff ratio up to 105 and sub-threshold slope down to 100mV/dec. HfO2/TiN gate stack is employed and the equivalent oxide thickness of 1.1 nm is achieved. The effective hole mobility of the transistors reaches 200cm2/V?s, which is 2.12 times the Si universal hole mobility.

Infrared reflectivity measurement is carried out for AlN films on sapphire substrates. The frequencies of the symmetry optical phonon E1(TO) in the temperature range from 77 K to 500 K are reported by fitting the experimental reflectivity with the classical multi-oscillators model. Taking the lattice thermal expansion and Klemens process of the phonon decay into account, along with the strain effect introduced by thermal mismatch between the film and the substrate, the temperature effect on the frequency of the optical phonon E1(TO) is revealed. It is shown that the shift of frequency is mainly attributed to the decay process while the strain effect induced by thermal mismatch plays a non-negligible role in the outcomes of the strength and damping parameters.

A novel silicon-on-insulator (SOI) trench metal-oxide-semiconductor field effect transistor (MOSFET) with a reduced specific on-resistance (Ron,sp) is presented. It features an oxide-filled trench and a non-depleted embedded p-type island (p-SOI). The oxide trench folds the drift region into a U-shape, resulting in a reduction in cell pitch and Ron,sp. The non-depleted p-island is employed to further reduce Ron,sp by increasing the optimized doping concentration of the drift region without deteriorating the breakdown voltage (BV). The simulation results show that the p-SOI decreases the Ron,sp to 10.2mΩcm2 from 17.4mΩcm2 of the conventional SOI MOSFET at the same BV.

We introduce a generalized joint density of states (GJDOS), which incorporates the coherent factors into the JDOS, to study quasiparticle interference (QPI) in superconductors. The intimate relation between the Fourier-transformed local density of states and GJDOS is revealed: they correspond respectively to the real and imaginary parts of a generalized impurity-response function, and particularly share the same angular factors and singular boundaries, as seen from our approximate analytic results for d-wave superconductors. Remarkably, our numerical GJDOS analysis agrees well with the QPI patten of d-wave cuprates and s±-wave iron-based superconductors. Moreover, we illustrate that the present GJDOS scenario can uncover the sign features of the superconducting gap and thus can be used to explore the pairing symmetry of the A1−xFe2—ySe2 (A=K, Cs, etc) superconductors.

Porous α-Fe2O3 nanowires are synthesized by a simple wet chemical method with a precursor of peroxyacetyl nitrate (PAN), and α-Fe2O3 nanoparticles are also synthesized in the same way except for the addition of PAN. Gas sensors are fabricated by coating the samples on ceramic tubes with Au signal electrodes and Ni-Cr heaters. A sensing investigation reveals that the porous α-Fe2O3 nanowires have a higher sensitivity compared to α-Fe2O3 nanoparticles at 260°C. The corresponding sensor response (Ra/Rg) is 18.2 at the maximum to 100 ppm acetone, and the response and recovery times are about 8 and 12 s, respectively. The porous and one-dimensional nanostructures of the porous α-Fe2O3 nanowires benefit for the gas-absorption and electrical-signal-transfer, and thus improve the sensor sensitivity consequentially.

A novel controllable hybrid-anode AlGaN/GaN field-effect rectifier (HA-FER) with low operation voltage (LOV) is proposed. Its mechanism can be explained by the field-controlled energy band model. This model reveals that the electric field in the AlGaN layer alters the energy band to result in a variation of the two-dimensional electron gas (2DEG) at AlGaN/GaN interface; the field can be changed by the thickness d of the AlGaN layer and the applied bias. As the d reduces below the critical thickness, the 2DEG vanishes and then the channel is pinched of. Therefore, the threshold voltage of HA-FER can be designed as low as 0 V leading to LOV (< 1 V). The analytical characteristic of the HA-FER is calculated and validated by the simulated results. These results also demonstrate that the forward properties of HA-FER are superior to the conventional SBD due to the high Schottky barrier.

We perform numerical simulations of the leakage current characteristics of an insulating thin film of SiO2 negatively charged by a low-energy nonpenetrating focused electron beam. For the formation of leakage current, electrons are demonstrated to turn from diffusion to drift after clearing the minimum potential barrier due to electron-hole separation. In the equilibrium state, the leakage current increases approximately linearly with the increasing primary beam current and energy. It also increases with the increasing film thickness and trap density, and with the decreasing electron mobility, in which the film thickness has a greater influence. Validated by some existing experiments, the simulation results provide a new perspective for the negative charging effects of insulating samples due to the low-energy focused electron beam.

We investigate numerically the influences of Gaussian white noise on the dynamical behaviors of power systems. The studied model is a three-bus system at some specific parameters, and it demonstrates a stable regime that is far from collapse. It is found that with the increasing noise intensity σ, power systems become unstable and fall into oscillations; as σ is further increased, noise-induced voltage collapse in power systems takes place. Our results confirm that the presence of noise has a detrimental effect on power system operation. Furthermore, the possible mechanism behind the action of noise is addressed based on a dynamical approach where the bifurcation of the system is analyzed. Our results may provide useful information for avoiding instability problems in power systems.

The neutron-capture process is traditionally postulated to be responsible for the nucleosynthesis of heavy elements beyond Fe. Based on the least squares method and solar isotopic abundances from the classical model, we estimate the relative contributions of the s- and r-processes to the abundance of neutron-capture elements in the metal-poor star HD 175305 from the component coefficients. Applying the calculated component coefficients C-r and C-s, the model predicts the isotopic fractions of elements Nd, Sm and Eu to be f(142+ 144) = 0.482, f(152+ 154) = 0.525 and f(151) = 0.450, respectively. As well as the observed abundances, the isotropic fractions are also consistent with the calculations. Finally, for the first time, we estimated the contribution percentage of the two neutron processes (the r-and s-processes) from the observed isotopic fractions of different elements in HD 175305, e.g. an r-process contribution of 67%(- 21%)(-32%) from the 4604 angstrom line of Sm.

A 1200-V thin-silicon-layer p-channel silicon-on-insulator (SOI) lateral double-diffused metal-oxide-semiconductor (LDMOS) transistor is designed. The device named INI SOI p-LDMOS is characterized by a series of equidistant high concentration n+ islands inserted at the interface of a top silicon layer and a buried oxide layer. Accumulation-mode holes, caused by the electric potential dispersion between the device surface and the substrate, are located in the spacing between two neighboring n+ islands, and greatly enhance the electric field of the buried oxide layer and therefore, effectively increase the device breakdown voltage. Based on a 2-μm-thick buried oxide layer and a 1.5-μm-thick top silicon layer, a breakdown voltage of 1224 V is obtained, resulting in the high electric field (608 V/μm) of the buried oxide layer.

We investigate how the random long-range interactions affect the synchronization features in networks of inertial ratchets, where each ratchet is driven by a periodic time-dependent external force, under the influence of an asymmetric periodic potential. It is found that for a given coupling strength C, the synchronization of the coupled ratchets is induced as the fraction of random long-range interactions p increases and the ratchet networks reach full synchronization for a larger p. It is also found that the system reaches synchronization more effectively for a stronger coupling strength.