Quantum key distribution using four-level particles

We present a quantum key distribution protocol based on four-level particle entanglement. Furthermore, a controlled quantum key distribution protocol is proposed using three four-level particles. We show that the two protocols are secure.     

Li+,Bi3+掺杂对Lu2O3∶Ho3+,Yb3+粉体发光性质的影响

采用高温固相法制备了Li+、Bi3掺杂Lu2O3∶Ho3,Yb3粉体.用X射线衍射仪分析了合成粉体的微结构,用场发射扫描电子显微镜观测了样品的形貌及尺寸,用紫外可见近红外荧光光谱仪分析了合成粉体的上转换发射光谱以及能级寿命.结果 表明:Li+、Bi3掺杂的Lu2O3∶Ho3,Yb3粉体,仍然保持Lu2O3立方相结构.Li+或Bi3掺杂后,合成粉体的分散性更好,颗粒更均匀,且更加接近球形,LI+掺杂后粉体颗粒尺寸明显增加.用980 nm激发,4;Li+或1.5; Bi3+掺杂后,合成粉体中Ho3的绿光光强分别提高了约3.9倍、2.8倍.随着Li+浓度的增加,合成粉体中Ho3的5S2能级寿命先增加后减小;随着Bi3浓度的增加,合成粉体中Ho3的5S2能级寿命逐渐减小.     

基于时间反转镜的自适应聚焦仿真研究

为在水下信号检测中消除水声信道的影响,实现最佳聚焦,在分析时间反转自适应聚焦原理的基础上,研究了时间反转镜(TRM)的自适应聚焦现象.在典型的水文条件下进行了TRM自适应聚焦的仿真研究.结果表明:在随机媒质中,TRM利用水声信道的相干多途特性获得聚焦增益,聚焦效果明显优于均匀媒质;聚焦信号的峰值比均匀媒质高23%.     

Fe原子能级和跃迁参数的研究

Fe原子有着丰富的谱线,其结构和跃迁光谱的研究在天体物理、等离子体物理、同位素分离和软X射线激光等领域中有着重要的指导意义.本文利用Cowan程序计算了 Fe原子3d64s2和3d64s4p组态的能级以及3d64s2-3d64s4p的跃迁能和跃迁波长.结果表明:从头计算的3d64s2和3d64s4p组态的能级与NIST...     

纳米材料量子尺寸效应的理解及应用

在理解纳米材料量子尺寸效应的基础上,对久保提出的分立平均能级间距与热能的关系公式δ=4EF与温度T之间的关系公式d03<1.078×T 10-14n-31m3,由此讨论临界粒径d0与温度T之间的关系,并进而应用公式举例计算纳米级金属颗粒出现量子尺寸效应的临界粒径。     

C_2^+ (X^4 Σ_g^-,1^4 Σ_u^+)离子体系解析势能函数、光谱常数和振动能级研究

采用多参考组态相互作用(MRCI)方法,结合aug-cc-pV6Z(AV6Z)基组,计算了C₂⁺(X⁴Σ_g^-,1⁴Σ_u⁺)的势能曲线,计算过程中考虑了Davidson修正和相对论效应,并将结果外推至完备基组(CBS)的极限.基于得到的单点能量,用最小二乘法方法进行了Murrell-Sorbie函数拟合,得到了势能函数解析式(APEF).基于APEF,计算了C₂⁺(X⁴Σ_g^-,1⁴Σ_u⁺)离子体系的离解能D_e,平衡核间距R_e,光谱常数ω_e,ω_eχ_e,B_e,α_e,结果与实验和其他理论计算值符合...     

在反转恢复测试中磁化矢量的演化特征:辐射阻尼效应

在强辐射阻尼存在下,水样(90% H₂O in D₂O)的反转恢复实验表明:当两脉冲的相位相差180°且反转脉冲角<180°时,或两脉冲相位一致但反转脉冲角>180°时,在检测期观测到的信号强度将不发生从负极大值到正极大值的突变;在同样的条件下,如果存在频率偏置,信号强度存在波动,即beating效应.只有当两脉冲的相位一致而反转脉冲角<180°时,或两脉冲的相位相差180°但反转脉冲角>180°时,在检测期信号强度才发生突变,即jumping效应.这些现象都可通过辐射阻尼理论予以合理地解释.另外,在检测期当磁化矢量运动到-z轴附近(对应于τ=T_rdln{tan[(π±δ)/2]}),信号强度与理论预计的偏差实际上与T₁弛豫效应有关.     

Transparency and Strong Gain Without Population Inversion in Photonic Bandgap Crystals

Without using the weak-field approximation,we investigate the transient properties of a Λ-type atom with one transition near resonant with a photonic bandgap edge.Whatever the initial state of the atom is,the atom can become transparent to a probe field,and strong gain without population inversion is also possible if the atom has been pre-excited.The defect mode formed by atomic doping can have a strong effect on the absorption properties of the atom.     

Magnetization reversal within Dzyaloshinskii—Moriya interaction under on-site Coulomb interaction in BiCrO3

First-principals calculations show that magnetization reversal is accompanied by the opposite sense of rotation of the neighboring oxygen octahedra along the [1 1 1] direction which is called the antiferrodistortive displacement in BiCrO3. The coupling between magnetization and antiferrodistortive distortion is mainly caused by Dzyaloshinskii- Moriya interaction which is driven by the eg-eg states antiferromagnetic interaction in Cr-3d. A critical value of on-site Coulomb interaction prohibiting the Dzyaloshinskii-Moriya interaction and thus the magnetization reversal is found to be 1.3 eV.