We demonstrate a simple technique to prepare and determine the desired internal quantum states in multi-Zeeman-sublevel atoms. By choosing appropriate coupling and pumping laser beams, atoms can be easily prepared in a desired Zeeman sublevel with high purity or in any chosen ground-state population distributions. The population distributions or state purities of such prepared atomic states can be determined by using a weak, circularlypolarized probe beam due to differences in transition strengths among different Zeeman sublevels. Preparing well-defined internal quantum states in multi-Zeeman-sublevel atoms (or spin-polarized quantum-state engineering) will be very important in demonstrating many interesting effects in quantum information processing with multi-level atomic systems.PACS numbers: 42.50.Gy, 32.80.Pj, 03.65.Wj 1 Preparing atoms into one specified internal quantum state and determining the population distribution in multi-Zeeman-sublevel atomic systems are very important in studying atom-field interactions, especially interesting schemes for quantum information processing such as light storage [1], quantum phase gate [2][3][4][5], and entanglement between atomic assemble and photons [6] or between a single trapped ion and a single photon [7].Demonstrations of these novel effects require more than two atomic energy levels and welldefined initial internal quantum state for the atoms, which can not be accomplished by simple optical pumping as in the case for a two-level atomic system. Although in most cases interesting effects can be experimentally demonstrated by simply considering degenerate Zeeman levels, so no specific ground-state population preparations are needed (as in the cases of electromagnetically induced transparency (EIT) [8-10] and photon storage [11]), there are many effects that demand better quantum-state preparation and determination in the multi-Zeeman-sublevel atomic systems. For example, in order to demonstrate quantum phase gate in multi-level atomic systems, such as the five-level M-type [3] and five-level combined M and tripod-type [5] systems, initial ground-state populations have to be prepared in specific Zeeman sublevels. Other examples include synthesis of arbitrary quantum states [12] and many other multi-level atomic systems for quantum information processing. Although specific atomic ground states were prepared in some of the previous experiments and the population distributions were estimated [6], no simple optical techniques have been developed, to the best of our knowledge, to determine the ground-state populations of the prepared internal quantum states of the atoms. Such measurements are very important in determining the coherent time of the photon storage [13], achieving large entanglement between photons and the atomic assemble [6], and realizing quantum phase gates due to cross-phase

SAC0307 (Sn-0.3mass%Ag-0.7mass%Cu) lead-free solder pastes were used to complete Cu/Cu joint by ultrasonic-assisted. Effect of nano-Ni particles and temperature on the performance of joint by ultrasonic-assisted with lead-free solder paste were investigated. The experimental results have shown that interfacial IMC of joint with SACP were typical scallop-type, but the type of interfacial IMC were serrated and became smoother after added nano-Ni particles. The IMC thickness was not more than 6.00 μm and the IMC thickness of SACP joint was slightly thick comparing with SACPC joint at the same temperature. Interfacial IMC of SACP joint at 210 C was mainly composed of a layer of thick Cu 6 Sn 5 and thin Cu 3 Sn, and the concentration gradients of Cu and Sn in IMC were also obviously. The composition of IMC was Cu 3 Sn 7 in SACPC joint at 210 C, there were no different and the composition was Cu 42.5 Sn 57.5 whether nano-Ni particles were added at 240 C. The strength of two kinds of joints were increased rst and then decreased with the increase of ultrasonic time at 210 C 220 C, but decreased in both joints at 240 C. The shear strength of SACP joint was only 31.59 MPa, but the shear strength of SACPC joint reached the peak value of 41.20 MPa at 5 s by ultrasonic-assisted at 210 C, were about 0.32 and 19.80 percent more than that of no ultrasonic-assisted. The shear strength of SACP joint and SACPC joint reached the peak value of 38.80 MPa and 41.96 MPa after ultrasonic vibration for 0 s at 240 C, but decreased to the minimum of 22.47 MPa and 21.11 MPa after ultrasonic-assisted at 5 s and 10 s, were about 42.09 and 49.69 percent less than that of no ultrasonic-assisted respectively. Ultrasound can help ll the solder seam to increase the shear strength, but slag inclusion and foreign gases would gather and grow up to lead decreasing of the shear strength at 210 C 220 C. Slag inclusion and foreign gases were wrapped into the seam and not easy to over ow under the liquid state in the liquidus nearby, would gather to the interface of IMC/solder and grow up to lead decreasing of the shear strength under the the ultrasonic vibration at 240 C. Nano-Ni particles also played a part in increasing the strength of joints.

Borophene is a new type of two-dimensional material with a series of unique and diversified properties. However, most of the research is still in its infancy and has not been studied in depth. Especially in the field of semiconductor optoelectronics, there is no related research on the modulation of photoelectric properties of borophene. In this work, we focus on the effect of doping on the photoelectric properties of borophene by using the first-principles pseudopotential plane wave method. We calculate the geometric structure, electronic structure, Mulliken population analysis, and optical properties of impurity (X = Al, Ga) doped α-sheet borophene. The results show that α-sheet borophene is an indirect band gap semiconductor with 1.396 eV. The band gap becomes wider after Al and Ga doping, and the band gap values are 1.437 eV and 1.422 eV, respectively. Due to the orbital hybridization between a small number of Al-3p electrons and Ga-4p state electrons and a large number of B 2p state electrons near the Fermi level, the band gap of borophene changes and the peak value of the electron density of states reduces after doping. Mulliken population analysis shows that the B0-B bond is mainly covalent bond, but there is also a small amount of ionic bond. However, when the impurity X is doped, the charge transfer between X and B atoms increases significantly, and the population of the corresponding X-B bonds decreases, indicating that the covalent bond strength of the chemical bonds in the doped system is weakened, and the chemical bonds have significant directionality. The calculation of optical properties shows that the static dielectric constant of the borophene material increases, and the appearance of a new dielectric peak indicates that the doping of Al and Ga can enhance the ability of borophene to store electromagnetic energy. After doping, the peak reflectivity decreases and the static refractive index n0 increases, which also fills the gap in the absorption of red light and infrared light by borophene materials. The research results provide a basis for the development of borophene materials in the field of infrared detection devices. The above results indicate that doping can modulate the photoelectric properties of α-sheet borophene.

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