We study the asymmetric decompositions of bound-state (BS) soliton solutions to the nonlinear Schrödinger equation. Assuming that the BS solitons are split into multiple solitons with different displacements, we obtain more accurate decompositions compared to the symmetric decompositions. Through graphical techniques, the asymmetric decompositions are shown to overlap very well with the real trajectories of the BS soliton solutions.

Quantum key distribution (QKD)-based quantum private query (QPQ) is a practical application of QKD, which relaxes the security condition of perfectly concealing a private query to a cheating-sensitive strategy. We propose a QPQ protocol based on the delegated QKD scheme (DQKD-based QPQ), in which two almost 'classical' clients (data user and database owner) can establish a 1-out-of-N oblivious key with the help of a cloud server with full quantum ability. Concretely, the two classical participants in the DQKD-based QPQ only need to access the quantum channel and reorder qubits, and the costly quantum operations, quantum state preparation and measurement are outsourced to a full quantum server in the cloud without leaking participants' privacy. The proposed protocol not only provides a cloud-based framework of QKD-based QPQ, but also obtains better security by a real-time security check, which can protect the security of the database and user against all potential attacks even if the quantum server is assumed to be a powerfully untrusted adversary.

We investigate the quantum Fisher information (QFI) dynamics of a dissipative two-level system in homodyne-mediated quantum feedback control. The analytical results demonstrate that the maximum values and stable values of the QFI can be greatly enhanced via feedback control. The quantum feedback plays a more evident role in the improvement of classical Fisher information. The classical part can reach a high stable value, while the quantum part eventually decays to zero whatever the feedback parameter is.

Using the adiabatic invariant action and applying the Bohr–Sommerfeld quantization rule and first law of black hole thermodynamics, a study of the quantization of the entropy and horizon area of a Kerr–Newman–de Sitter black hole is carried out. The same entropy spectrum is obtained in two different coordinate systems. It is also observed that the spacing of the entropy spectrum is independent of the black hole parameters. Also, the corresponding quantum of horizon area is in agreement with the results of Bekenstein.

In the framework of the Skyrme–Hartree–Fock–Bogoliubov approach with the SkT interaction, the pairing effects on the proton bubble structures of $^{46}$Ar and $^{206}$Hg are discussed. In calculations, three kinds of pairing forces (volume, surface and mixed pairing interactions) are used. For $^{46}$Ar, it is shown that the bubble structure with the volume pairing is almost the same as that with the mixed pairing. The bubble with the surface pairing is less pronounced than those with the volume and mixed pairings. Analyzing the density distributions and occupation probabilities of the proton $s$ states and the quasi-degeneracy between the proton 2$s_{1/2}$ and 1$d_{3/2}$ orbitals, we explain the difference between the bubble structure with the surface pairing and those with the volume and mixed pairings. For $^{206}$Hg, it is seen that the proton density distribution with the surface pairing is different from those with the volume and mixed pairings in the whole region of the radial distance. In addition, it is found that the bubbles with the three pairing forces are different from each other and the least pronounced bubble is obtained with the surface pairing. Thus the selection of the pairing force is important for the study of the nuclear bubble structure.

A laser-diode pumped passive Q-switched Nd:YAG/Cr$^{4+}$:YAG laser with quick tunable pulse-width capability is studied and experimentally demonstrated. By focusing the auxiliary controlling laser beam onto a Cr$^{4+}$:YAG crystal and thereby changing the initial transmission of the Cr$^{4+}$:YAG crystal, laser pulses with different pulse widths can be achieved. The obtained laser pulse width is tunable in the range of 550–1492 ps with a fixed cavity length of 7 mm. The laser can be used to achieve different pulse widths between two pulses in the range of sub-nanosecond to a few tens of nanoseconds.

Efficiently routing the quantum signals between different channels is essential in a quantum multichannel network. We investigate the quantum routing in a multi-cross-shaped waveguide coupled to driven three-level systems. Numerical results show that the high routing capacity transferring from the input channel to the other channels can be explicitly enhanced by effective reflection potentials. The proposed system may be utilized as a scalable quantum device to control single-photon routing.

The zero refractive index properties of two-dimensional photonic crystals (PCs) are studied theoretically. Three necessary conditions for PCs to mimic the zero index materials (ZIMs) are obtained. In addition, through a comparative study of the properties for two representative PC structures with different types of Dirac cones, we find that the PC with a Dirac-like cone which meets the three necessary conditions does not behave as a ZIM in some cases. Further analysis shows that its non-zero index properties originate from the flat dispersion band. These findings clarify the fundamental physical issue of which type of Dirac cone PC can mimic a real ZIM.

We theoretically investigate the transparency effect with a hybrid system composed of a photonic molecule and dipole emitter. It is shown that the transparency effect incorporates both the coupled resonator-induced transparency (CRIT) effect and the dipole-induced transparency (DIT) effect. It is found that the superposed transparency windows are consistently narrower than the CRIT and DIT transparency windows. Benefiting from the superposed transparency effect, the photonic Faraday rotation effect could be realized in the photonic molecule system, which is useful for entanglement generation and quantum information processing.

A dynamical propagation model coupled to the oscillation of cavitation bubbles is applied to describe the imploding acoustic field in a cavitating liquid where the acoustic waves transmit from the outside to the inside of a circle disk. Numerical simulation shows that the imploding ability of a ring source can elevate the sound pressure or partly eliminate the decay due to both the bulk attenuation and the attenuation caused by cavitation. However, the imploding ability is limited and there exists a critical radius. When the radius of the disk is larger than the critical one, the imploding ability is not enough to eliminate the attenuation. Fortunately, the cavitation region can be effectively expanded if a hot plate is attached under the center of the disk because the cavitation threshold is related to the temperature of the liquid, which means that a region with good uniformity of cavitation can be enhanced by adjusting the temperature difference between the central and side liquid.

We investigate single-axis acoustic levitation using standing waves to levitate particles freely in a medium bounded by a driver and a reflector. The acoustic pressure at the pressure antinode of the standing wave counteracts the downward gravitational force of the levitating object. The optimal relationship between the air gap and the driving frequency leads to resonance and hence maximization of the levitating force. Slight deviation from the exact resonance condition causes a reduction in acoustic pressure at the pressure antinodes. This results in a significant reduction of the levitating force. The driving frequency is kept constant while the air gap is varied for different conditions. The optimal air gap for maximizing the levitation force is studied for first three resonance modes. Furthermore, a levitating particle is introduced between the driver and the reflector. The dependence of the resonance condition on the size of the levitating particle as well as the position of the particle between the driver and the reflector has also been studied. As the size of the levitating particle increases, the resonance condition also gets modified. Finite element results show a good agreement with the validated results available in the literature. Furthermore, the finite element approach is also used to study the variation of acoustic pressure at the pressure antinode with respect to the size of the reflector. The optimum diameter of the reflector is calculated for maximizing the levitating force for three resonance modes.

The superposition dynamics of two confronting ultrasonic waves and their levitation capability for centimeter-sized thin disks are investigated by numerical analyses and validated by experiments. The sound pressure simulation reveals that two opposite ultrasonic waves provide a more effective standing-wave field than a single ultrasonic wave when the diameter of disk-shaped object approaches the wavelength scale. The dynamic superposition of two confronting beams facilitates the acoustic levitation of the clay disk and aluminum disk with diameters of 0.97$\lambda $ and 0.90$\lambda $. The acoustic radiation forces exerting on these thin disks are measured experimentally, which exhibit a better levitation stability for the centimeter-sized thin disks. The equilibrium levitation positions of the two disks are located near the sound pressure node, and the maximum acoustic radiation pressure on their surfaces is less than one percent of the maximum sound pressure.

We study the Brownian motion of a single ellipsoidal particle diffusing in a narrow channel by video-microscopy measurement. The experiments allow us to obtain the trajectories of ellipsoids and measure the diffusion coefficients. It is found that the channel constraints lead to suppression of the particle motion, especially the perpendicular motion to the channel, and the long axis of the particle tends to be parallel to the channel. A stable stratification phenomenon is observed, which is rarely discussed in studies of spherical particles. We also derive an approximate solution of theoretical prediction with the method of reflections, and obtain numerical simulation results using finite element software. They are proven to be effective by comparing them with the experimental results. All of these indicate that the aspect ratio and size of ellipsoid, the width of channel, and the transverse position distinctly affect the Brownian motion of ellipsoids.

Double-well potentials are used for molecular dynamics simulation in monatomic systems. The potentials change as their parameters are adjusted, resulting in different structures. Of particular interest, we obtain decagonal and dodecagonal quasicrystals by simulations. We also verify the results and explain the formation of quasicrystals from the perspective of potential energy.

A potential superhard $o$-BC$_{4}$N with $Imm2$ space group is identified by ab initio evolutionary methodology using CALYPSO code. The structural, electronic and mechanical properties of $o$-BC$_{4}$N are investigated. The elastic calculations indicate that $o$-BC$_{4}$N is mechanically stable. The phonon dispersions imply that this phase is dynamically stable under ambient conditions. The structure of $o$-BC$_{4}$N is more energetically favorable than $g$-BC$_{4}$N above the pressure of 25.1 GPa. Here $o$-BC$_{4}$N is a semiconductor with an indirect band gap of about 3.95 eV, and the structure is highly incompressible with a bulk modulus of 396.3 GPa and shear modulus of 456.0 GPa. The mechanical failure mode of $o$-BC$_{4}$N is dominated by the shear type. The calculated peak stress of 58.5 GPa in the (100)[001] shear direction sets an upper bound for its ideal strength. The Vickers hardness of $o$-BC$_{4}$N reaches 78.7 GPa, which is greater than that of $t$-BC$_{4}$N and $bc$-BC$_{4}$N proposed recently, confirming that $o$-BC$_{4}$N is a potential superhard material.

A closed two-temperature-zone chemical vapor deposition (CVD) furnace was used to grow monolayer molybdenum disulfide (MoS$_{2}$) by optimizing the temperature and thus the evaporation volume of the Mo precursor. The experimental results show that the Mo precursor temperature has a large effect on the size and shape transformation of the monolayer MoS$_{2}$, and at a lower temperature of $ < $760$^{\circ}\!$C, the size of the triangular MoS$_{2}$ increases with the elevating temperature, while at a higher temperature of $>$760$^{\circ}\!$C, the shape starts to change from a triangle to a truncated triangle. A large-area triangular monolayer MoS$_{2}$ with a side length of 145 μm is achieved at 760$^{\circ}\!$C. Further, the as-grown monolayer MoS$_{2}$ is used to fabricate back-gated transistors by means of electron beam lithography to evaluate the electrical properties of MoS$_{2}$ thin films. The MoS$_{2}$ transistors with monolayer MoS$_{2}$ grown at 760$^{\circ}\!$C exhibit a high on/off current ratio of 10$^{6}$, a mobility of 1.92 cm$^{2}$/Vs and a subthreshold swing of 194.6 mV/dec, demonstrating the feasible approach of CVD deposition of monolayer MoS$_{2}$ and the fabrication of transistors on it.

Mn$_{0.3}$Zn$_{0.3}$Co$_{x}$Fe$_{2.4-x}$O$_{4}$ series magnetic nanoparticles are prepared by the high-temperature organic solvent method, and Mn$_{0.3}$Zn$_{0.3}$Co$_{x}$Fe$_{2.4-x}$O$_{4}$@SiO$_{2}$ composite nanoparticles are prepared by the reverse microemulsion method. The as-prepared samples are characterized, and the results show that the magnetic anisotropy constant of nanoparticles increases with the cobalt content, and the magnetic thermal induction shows a trend of increasing first and then decreasing. The optimal magnetic thermal induction is obtained at $x=0.12$ with a specific loss power of 2086 w/g$_{\rm metal}$, which is a bright prospect in clinical magnetic hyperthermia.

The electronic structure of perfect ammonium dihydrogen phosphate (ADP) and defective ADP with an oxygen (O) vacancy are calculated by screened-exchange hybrid density functional HSE06. The optimized structural parameters of the defective ADP crystal are analyzed. The PO$_{4}$ tetrahedron with an O vacancy is distorted and its symmetry is broken. The band gap of the defective ADP with an O vacancy is about 1.5 eV lower than the perfect ADP, which is due to the new O vacancy defect states near the valence band maximum. Moreover, more peaks appear in the low-energy region (lower than 6 eV) in the curves of the linear optical properties for the defective ADP. The results indicate that the O vacancy will significantly influence the laser damage performance of ADP crystals.

An approach for studying the influence of nano-particles on the structural properties of deposited thin films is proposed. It is based on the molecular dynamic modeling of the deposition process in the presence of contaminating nano-particles. The nano-particle is assumed to be immobile and its interaction with film atoms is described by a spherically symmetric potential. The approach is applied to the investigation of properties of silicon dioxide films. Visualization tools are used to investigate the porosity associated with nano-particles. The structure of the film near the nano-particle is studied using the radial distribution function. It is found that fluctuations of film density near the nano-particles are essentially different in the cases of low-energy and high-energy deposition processes.

The combination of magnetic trap (MT) and fluorescence resonant energy transfer (FRET) allows for nanoscale measurements of configurational changes of biomolecules under force. However, the magnetic bead involved in MT experiments introduces a substantial amount of background fluorescence which reduces the signal-to-noise ratio (SNR) of FRET significantly. Moreover, the short lifetime of the dye used in FRET limits the total sampling time when combined with MT. Here we use a moveable tube lens to adjust the wave front in the light pathway of MT so that both images of the magnetic bead and the fluorescent signals can be detected when long DNA handles are used to reduce the auto-fluorescence of the magnetic bead. We utilize the internal trigger of an electron multiplying charge-coupled device camera to control a shutter so that the dye can be excited intermittently when long time measurement of FRET is needed. As a demonstration of the hybrid technique, we observe the unfolding/refolding dynamics of a DNA hairpin and measure the DNA unwinding activity of the saccharomyces cerevisiae Pif1 (Pif1). Our results show that the unwinding burst of Pif1 under external force is different from that without the force. In addition, the improvement provides a better SNR and a longer sampling time in experiments in the MT-FRET assay.