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<jats:p>Shenvi <jats:italic>et al.</jats:italic> have proposed a quantum algorithm based on quantum walking called Shenvi–Kempe–Whaley (SKW) algorithm, but this search algorithm can only search one target state and use a specific search target state vector. Therefore, when there are more than two target nodes in the search space, the algorithm has certain limitations. Even though a multi-objective SKW search algorithm was proposed later, when the number of target nodes is more than two, the SKW search algorithm cannot be mapped to the same quotient graph. In addition, the calculation of the optimal target state depends on the number of target states <jats:italic>m</jats:italic>. In previous studies, quantum computing and testing algorithms were used to solve this problem. But these solutions require more Oracle calls and cannot get a high accuracy rate. Therefore, to solve the above problems, we improve the multi-target quantum walk search algorithm, and construct a controllable quantum walk search algorithm under the condition of unknown number of target states. By dividing the Hilbert space into multiple subspaces, the accuracy of the search algorithm is improved from <jats:italic>p</jats:italic> <jats:sub>c</jats:sub> = (1/2) – <jats:italic>O</jats:italic>(1/<jats:italic>n</jats:italic>) to <jats:italic>p</jats:italic> <jats:sub>c</jats:sub> = 1 – <jats:italic>O</jats:italic>(1/<jats:italic>n</jats:italic>). And by adding detection gate phase, the algorithm can stop when the amplitude of the target state becomes the maximum for the first time, and the algorithm can always maintain the optimal number of iterations, so as to reduce the number of unnecessary iterations in the algorithm process and make the number of iterations reach <jats:inline-formula> <jats:tex-math> <?CDATA ${t}_{{\rm{f}}}=(\pi /2)\sqrt{{2}^{n-2}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>t</mml:mi> <mml:mi mathvariant="normal">f</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mo stretchy="false">(</mml:mo> <mml:mi>π</mml:mi> <mml:mo>/</mml:mo> <mml:mn>2</mml:mn> <mml:mo stretchy="false">)</mml:mo> <mml:msqrt> <mml:mrow> <mml:msup> <mml:mn>2</mml:mn> <mml:mrow> <mml:mi>n</mml:mi> <mml:mo>−</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:msqrt> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_31_4_040307_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>.</jats:p>

<jats:p>We studied the rectified transport of underdamped particles subject to phase lag in an asymmetric periodic structure. When the inertia effect is considered, it is possible to observe reversals of the average velocity with small self-propelled force, whereas particles always move in the positive direction with large self-propelled force. The introduction of phase lag leads particles to follow circular orbits and suppress the polar motion. In addition, this can adjust the direction of particle motion. There exists an optimal value of polar interaction strength at which the rectification is maximal. These results open the way for many application processes, such as spatial sorting of particles mixture and separation based on their physical properties.</jats:p>

<jats:p>We systematically test the performance of several Monte Carlo update schemes for the (2 + 1)d <jats:italic>XY</jats:italic> phase transition of quantum rotor model. By comparing the local Metropolis (LM), LM plus over-relaxation (OR), Wolff-cluster (WC), hybrid Monte Carlo (HM), hybrid Monte Carlo with Fourier acceleration (FA) schemes, it is clear that among the five different update schemes, at the quantum critical point, the WC and FA schemes acquire the smallest autocorrelation time and cost the least amount of CPU hours in achieving the same level of relative error, and FA enjoys a further advantage of easily implementable for more complicated interactions such as the long-range ones. These results bestow one with the necessary knowledge of extending the quantum rotor model, which plays the role of ferromagnetic/antiferromagnetic critical bosons or <jats:italic>Z</jats:italic> <jats:sub>2</jats:sub> topological order, to more realistic and yet challenging models such as Fermi surface Yukawa-coupled to quantum rotor models.</jats:p>

<jats:p>The dynamics of C + H<jats:sub>2</jats:sub> → H + CH reaction is theoretically studied using the quasiclassical trajectory and quantum mechanical wave packet methods. The analysis of reaction probabilities, integral cross sections, and rate coefficients reveal the essential Coriolis coupling effects in the quantum mechanical wave packet calculations. The calculated polarization-dependent differential cross section, <jats:italic>P</jats:italic>(<jats:italic>θ<jats:sub>r</jats:sub> </jats:italic>) and <jats:italic>P</jats:italic>(<jats:italic>ϕ<jats:sub>r</jats:sub> </jats:italic>) show that the <jats:italic> <jats:bold>j</jats:bold> </jats:italic>′ of product rotational angular momentum is not only aligned along the <jats:italic>y</jats:italic> axis and the direction of the vector <jats:italic> <jats:bold>x</jats:bold> </jats:italic> + <jats:italic> <jats:bold>z</jats:bold> </jats:italic>, but also strongly oriented along the positive <jats:italic>y</jats:italic> axis.</jats:p>

<jats:p>Debye-screening effects on the electron-impact excitation (EIE) processes for the dipole-allowed transition 1s<jats:sup>2</jats:sup> <jats:sup>1</jats:sup> S → 1s2p <jats:sup>1</jats:sup>P in He-like Al<jats:sup>11+</jats:sup> and Fe<jats:sup>24+</jats:sup> ions are investigated using the fully relativistic distorted-wave methods with the Debye–Hückel (DH) model potential. Debye-screening effects on the continuum-bound (CB) interaction and target ion are discussed, both of which result in reduction of EIE cross sections. This reduction due to screening on the CB interaction is dominant. The non-spherical and spherical DH potentials are adopted for considering the screening effect on the CB interaction. It is found that the spherical DH potential could significantly overestimate the influence of plasma screening on EIE cross sections for multielectron He-like ions.</jats:p>

<jats:p>The photonic crystal structure has attracted much attention due to its ability to confine light. In this paper, we present our study on an improved Smith–Purcell radiation from a simple metal photonic crystal excited by moving electrons. Different from the wide-band Smith–Purcell radiation from a single metal grating, the results show that the injected electrons could induce more dipole oscillations inside the multi-grating structure, and it leads to the enhancement of the radiation intensity. In addition, there are strong resonances in metal multi-grating structure, and the resonance characteristics may narrow the radiation band, which leads to a radiation with an obvious peak in the spectrum. Therefore, the multi-grating structure has the ability to enhance the radiation intensity and shape the radiation frequency band. By optimizing the structure parameters, coherent and tunable Smith–Purcell radiation can be realized, and it provides a potential way to develop band-controllable light or THz radiation source.</jats:p>

<jats:p>We propose and analyze an instantaneous frequency measurement system by using optical power monitoring technique with improved resolution. The primary component adopted in the proposal is a dual-polarization quadrature phase shift keying (DP-QPSK) modulator which is used to modulate the microwave signal that has a designed time delay and phase shifting. The generated optical signal is sent to polarization beam splitter (PBS) in DP-QPSK modulator. Owing to the complementary transmission nature of polarization interference introduced by PBS, the frequency information is converted into the optical power and the relationship between the amplitude comparison function (ACF) and microwave frequency to be measured is established. Thus, the frequency of the microwave signal can be easily measured through monitoring the optical powers of the two output ports of the PBS. Furthermore, by adjusting the direct current (DC) biases of the DP-QPSK modulator instead of changing the electrical delay, the measurement range and resolution can be switched. In this paper, the basic principle of the instantaneous frequency measurement system is derived in detail, and simulation has been performed to investigate the resolution, the measurement range, and the influence of imperfection devices. The proposed scheme is wavelength-independent and its measurement range is switchable, which can avoid the laser wavelength drifting problem and thus greatly increasing the system flexibility.</jats:p>

<jats:p>Photoacoustic imaging is a potential candidate for <jats:italic>in vivo</jats:italic> brain imaging, whereas, its imaging performance could be degraded by inhomogeneous multi-layered media, consisted of scalp and skull. In this work, we propose a low-artifact photoacoustic microscopy (LAPAM) scheme, which combines conventional acoustic-resolution photoacoustic microscopy with scanning acoustic microscopy to suppress the reflection artifacts induced by multi-layers. Based on similar propagation characteristics of photoacoustic signals and ultrasonic echoes, the ultrasonic echoes can be employed as the filters to suppress the reflection artifacts to obtain low-artifact photoacoustic images. Phantom experiment is used to validate the effectiveness of this method. Furthermore, LAPAM is applied for <jats:italic>in-vivo</jats:italic> imaging mouse brain without removing the scalp and the skull. Experimental results show that the proposed method successfully achieves the low-artifact brain image, which demonstrates the practical applicability of LAPAM. This work might improve the photoacoustic imaging quality in many biomedical applications which involve tissues with complex acoustic properties, such as brain imaging through scalp and skull.</jats:p>

<jats:p>Contact force in a clearance joint affects the dynamic characteristics and leads to nonlinear response of the mechanism. It is necessary to assess the nonlinearity of contact force quantitatively. Therefore, a new method named contact-force entropy weight is proposed in this paper. This method presents a comprehensive description of the judgment matrix in the <jats:italic>X</jats:italic>, <jats:italic>Y</jats:italic>, and <jats:italic>Z</jats:italic> directions. To assess the influence degrees of different clearances and angular velocities on the contact force, the method is applied to numerical calculation and simulation of a six-bar mechanism with a clearance joint to illustrate its application and investigate the influence degree of angular velocity and clearance on the contact force. By combining the simulation results and theoretical calculations, the influence degrees of different clearances and angular velocities on the contact-force entropy weight of the six-bar mechanism with a clearance joint are revealed. It is found that the angular velocity has a significant influence on the contact force entropy weight of the clearance joint, showing that the contact-force entropy weight is a feasible new method of assessing non-linearity of contact force quantitatively. The method gives a theoretical reference for quantitatively analyzing the nonlinear dynamics.</jats:p>

<jats:p>Diffusion of colloidal particles in microchannels has been extensively investigated, where the channel wall is either a no-slip or a slip-passive boundary. However, in the context of active fluids, driving boundary walls are ubiquitous and are expected to have a substantial effect on the particle dynamics. By mesoscale simulations, we study the diffusion of a chemically active colloidal particle in composite channels, which are constructed by alternately arranging the no-slip and diffusio-osmotic boundary walls. In this case, the chemical reaction catalyzed by the active colloidal particle creates a local chemical gradient along the channel wall, which drives a diffusio-osmotic flow parallel to the wall. We show that the diffusio-osmotic flow can significantly change the spatial distribution and diffusion dynamics of the colloidal particle in the composite channels. By modulating the surface properties of the channel wall, we can achieve different patterns of colloidal position distribution. The findings thus propose a novel possibility to manipulate colloidal diffusion in microfluidics, and highlight the importance of driving boundary walls in dynamics of colloidal particles in microchannels.</jats:p>