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<jats:p> <jats:italic>We analyze the effect of electrode diameter and thickness on the mass sensitivity. Through the theoretical approximate calculation, we find that the mass sensitivity does not change monotonically with electrode diameter and there is a maximum point. The optimum electrode diameter corresponding to the maximum mass sensitivity varies with the electrode thickness. For a particular electrode diameter, a quartz crystal microbalance (QCM) with thick electrode has a higher mass sensitivity. A proper plating experiment using 35 QCMs with different electrode diameters and thicknesses verifies this finding. The present study further reveals how electrode size affects mass sensitivity and is helpful for QCM design</jats:italic>.</jats:p>

<jats:p> <jats:italic>We report the creation of the first mixture of <jats:sup>6</jats:sup>Li and <jats:sup>88</jats:sup>Sr atoms in an optical dipole trap. Using this mixture, a measurement of the interspecies thermalization process is carried out and the previously unknown interspecies s-wave scattering length between <jats:sup>6</jats:sup>Li and <jats:sup>88</jats:sup>Sr atoms is extracted to be <jats:inline-formula> <jats:tex-math><?CDATA $|{a}_{{}^{{\rm{6}}}Li{-}^{88}Sr}|=({380}_{-100}^{+160}){a}_{0}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo stretchy="false">|</mml:mo> <mml:msub> <mml:mi>a</mml:mi> <mml:mrow> <mml:msup> <mml:mrow /> <mml:mn>6</mml:mn> </mml:msup> <mml:mi>L</mml:mi> <mml:mi>i</mml:mi> <mml:msup> <mml:mo>−</mml:mo> <mml:mrow> <mml:mn>88</mml:mn> </mml:mrow> </mml:msup> <mml:mi>S</mml:mi> <mml:mi>r</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">|</mml:mo> <mml:mo>=</mml:mo> <mml:mo stretchy="false">(</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>380</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>100</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>160</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo stretchy="false">)</mml:mo> <mml:msub> <mml:mi>a</mml:mi> <mml:mn>0</mml:mn> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_7_073401_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> with a<jats:sub>0</jats:sub> being the Bohr radius from the rate of interspecies thermalization</jats:italic>.</jats:p>

<jats:p> <jats:italic>We obtain bi-component Coulomb crystals using laser-cooled <jats:sup>40</jats:sup>Ca<jats:sup>+</jats:sup> ions to sympathetically cool <jats:sup>9</jats:sup>Be<jats:sup>+</jats:sup> ions in a linear Paul trap. The shell structures of the bi-component Coulomb crystals are investigated. The secular motion frequencies of the two different ions are determined and compared with those in the single-component Coulomb crystals. In the radial direction, the resonant motion frequencies of the two ionic species shift toward each other due to the strong motion coupling in the ion trap. In the axial direction, the motion frequency of the laser-cooled <jats:sup>40</jats:sup>Ca<jats:sup>+</jats:sup> is impervious to the sympathetically cooled <jats:sup>9</jats:sup>Be<jats:sup>+</jats:sup> ions because the spatially separation of the two different ionic species leads to the weak motion coupling in the axial direction</jats:italic>.</jats:p>

<jats:p> <jats:italic>Spatial characteristics of Thomson scattering spectra are studied for an electron moving in the circularly polarized laser field in the presence of a strong uniform magnetic field. The results show that the angular distributions of the spectra with respect to the azimuthal and polar angles exhibit different symmetries, respectively, which depend on the fields and electron parameters sensitively and significantly. Moreover, for relatively large parameters such as high laser intensity, high magnetic resonance parameter as well as large initial momentum of electron, the two lobes in spectra tend to the laser-propagating direction so that the radiation can be collimated in the forward direction. Furthermore, an important finding is that by choosing the appropriate fields and initial momentum of electron, the high frequency part of the Thomson scattering spectra can reach the frequency range of soft x-ray, in which a high radiation power per solid angle as ∼10<jats:sup>11</jats:sup> a.u. can be obtained</jats:italic>.</jats:p>

<jats:p> <jats:italic>We demonstrate a Fe:ZnSe laser gain-switched by a 2.9 <jats:italic>μ</jats:italic>m ZnGeP<jats:sub>2</jats:sub> optical parametric oscillator under pulse repetition frequency of 1 kHz at liquid nitrogen temperature of 77 K. The maximum output power is 63 mW with pulse duration of 34.4 ns. The wavelength covers 3686.6–4088.6 nm and centers at 3897.7 nm. The output power decreases with increasing the temperature of the crystal in 77–222 K.</jats:italic> </jats:p>

<jats:p> <jats:italic>We report the generation of heralded single photons with Gaussian-shape temporal waveforms through the spatial light modulation technique in an atomic ensemble. Both the full width at half maximum and the peak position of the Gaussian waveform can be controlled while the single photon nature holds well. We also analyze the bandwidth of the generated single photons in frequency domain and show how the sidebands of the frequency spectrum are modified by the shape of the temporal waveform. The generated single photons are especially suited for the realization of high efficiency quantum storage based on electromagnetically induced transparency.</jats:italic> </jats:p>

<jats:p> <jats:italic>Nanosecond pulse generation is demonstrated in a mode-locked erbium-doped fiber laser (EDFL) utilizing a samarium oxide (Sm<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>) film. The Sm<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> film exhibits a modulation depth of 33%, which is suitable for mode-locking operation. The passively pulsed EDFL operates stably at 1569.8 nm within a pumping power from 109 to 146 mW. The train of generated output pulses has a pulse width of 356 nm repeated at a fundamental frequency of 0.97 MHz. The average output power of 3.91 mW is obtained at a pump power of 146 mW, corresponding to 4.0 nJ pulse energy. The experimental result indicates that the proposed Sm<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> saturable absorber is viable for the construction of a flexible and reliably stable mode-locked pulsed fiber laser operating in the 1.5 <jats:italic>μ</jats:italic>m region.</jats:italic> </jats:p>

<jats:p> <jats:italic>We propose and demonstrate a new approach for a high power pulse laser reflection sequence combination with a fast steering mirror (FSM). This approach possesses significant advantages for lasers combining with a variety of output power, wavelength, pulse duration, repetition rates and polarization. The maximum number of laser routes participating in combination principally depends on the FSM’s adjustment time of the step response, lasers’ repetition rates and pulse duration. A proof-of-principle experiment is performed with two 2-kW level pulsed beams. The results indicate that the combined beam has an excellent pointing stability with rms pointing jitter ∼8.5 μrad. Meanwhile, a high combining efficiency of 98.6% is achieved with maintaining good beam quality.</jats:italic> </jats:p>

<jats:p> <jats:italic>For an electron-electron collision with characteristic scale length larger than the relative gyro-radius of the two colliding electrons, when the initial relative parallel kinetic energy cannot surmount the Coulomb repulsive potential, reflection will occur with interchange of the parallel velocities of the two electrons after the collision. The Fokker–Planck approach is employed to derive the electron collision term <jats:inline-formula> <jats:tex-math><?CDATA ${{\mathscr{C}}}_{{\rm{R}}}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi mathvariant="script">C</mml:mi> <mml:mi mathvariant="normal">R</mml:mi> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_7_075201_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> describing parallel velocity scattering due to the reflections for a magnetized plasma where the average electron gyro-radius is much smaller than the Debye length but much larger than the Landau length. The electron parallel velocity friction and diffusion coefficients due to the reflections are evaluated, which are found not to depend on the electron perpendicular velocity. By studying the temporal evolution of the <jats:italic>H</jats:italic> quantity due to <jats:inline-formula> <jats:tex-math><?CDATA ${{\mathscr{C}}}_{{\rm{R}}}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi mathvariant="script">C</mml:mi> <mml:mi mathvariant="normal">R</mml:mi> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_7_075201_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>, it is found that <jats:inline-formula> <jats:tex-math><?CDATA ${{\mathscr{C}}}_{{\rm{R}}}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi mathvariant="script">C</mml:mi> <mml:mi mathvariant="normal">R</mml:mi> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_7_075201_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> eventually makes the system relax to a state in which the electron parallel velocity distribution is decoupled from the perpendicular velocity distribution.</jats:italic> </jats:p>

<jats:p> <jats:italic>Structural, electronic and magnetic properties of La-, Ce-, Pr-, Nd-, Pm-, Sm- and Eu-doped <jats:italic>β</jats:italic>-graphyne are investigated by comprehensive <jats:italic>ab initio</jats:italic> calculation based on density functional theory. The adsorption energies indicate that the dopings are suitable. The doped <jats:italic>β</jats:italic>-graphyne undergoes transition from semiconductor to metal. Furthermore, the doping of Nd, Pm, Sm and Eu atoms can induce magnetization. The results are useful for spintronics and the design of future electronic devices.</jats:italic> </jats:p>