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991.
通过对比分立变量量子信息过程和连续变量量子信息过程的差别,利用相干态比较容易获得的这个特点,提出一种方案制备三个腔场的W型纠缠相干态.方案基于Λ型三能级原子与单模腔场的简并Raman 相互作用.三个相同的腔初始分别处于相干态,三个相同的原子初始处于W型纠缠态,通过三个原子分别与三个腔的Raman相互作用、选择适当的相互作用时间并探测作用后的三个原子,三个腔场坍缩为W型纠缠相干态.在原子与腔的相互作用过程中原子不处于高能级,可以忽略原子的自发辐射,系统的相干性能够得到较好的维持.基于当前的腔量子电动力学技术,相信方案能在实验上实现.该方案制备的三个腔场W型纠缠相干态有望在连续变量量子信息过程中有重要的应用价值.文中将方案推广到制备n(n〉3)个腔场的W型纠缠相干态. 相似文献
992.
993.
高斯光束在外加空间调制电场的光折变晶体中的演化 总被引:1,自引:0,他引:1
研究了高斯光束在外加空间调制电场的光折变晶体中的演化,结果表明,在不同的外加调制电场作用下高斯光束的光场分布会随着外电场变化而被调制。重点研究了同相位和反相位以及相位差为π/2的高斯光束在外加空间调制电场的光折变晶体中的相互作用,在外加空间分布线性增加电场作用下出现了许多新的实用特性,通过调整外加电场分布,可以让两同相位相干光靠得更近而不发生融合,也可以让两靠得很近的反相位光束可控偏转,还可以控制相位差为π/2的两相干光束进行能量转移。这种连续变化的电场可以用阶梯分布的电场替代,为工程实现提供了可能。 相似文献
994.
M. V. Kartikeyan E. Borie M. Thumm 《International Journal of Infrared and Millimeter Waves》2007,28(8):611-619
A design concept of a 250 GHz, ≈ 50 W, CW, second harmonic gyrotron for spectroscopy will be presented in this paper. Mode
competition, in particular with regard to competition with first harmonic modes, and mode selection procedures are carefully
investigated by considering various candidate modes and the TE6,2 and TE6,3 modes are chosen as probable operating modes. Cold cavity and self-consistent calculations of power and efficiency are carried
out to determine optimum parameters for these two modes. The results indicate that an output power of well over 50 W, CW can
be achieved. 相似文献
995.
Shihui Jiao Guangsheng Pang Hongwei Liang Yan Chen Shouhua Feng 《Journal of nanoparticle research》2007,9(4):605-610
Nanoparticles and nanorods of CuSb2O6 are prepared by hydrothermal method and its high temperature α-phase is stabilized at room temperature. The average size
of the nanoparticles is ca. 13.7 nm. The nanorods, with a width of ca. 20 nm and an aspect ratio of ca. 5, are the agglomerates
composing of smaller nanoparticles with an average size of ca. 8.3 nm. Compared with the high temperature α-phase of bulk
sample at 400 K, the lattice of nanophases elongated in ab plane and compressed along c direction. The CuSb2O6 nanoparticles exhibit predominant paramagnetic phenomenon. The difference in magnetic properties of the nanoparticles and
nanorods indicates the interfacial interaction of agglomerated nanoparticles. 相似文献
996.
A magnon–phonon interaction model is developed on the basis of two-dimensional square Heisenberg ferromagnetic system. By using Matsubara Green function theory transverse acoustic phonon excitation is studied and transverse acoustic phonon excitation dispersion curves is calculated on the main symmetric point and line in the first Brillouin zone. On line Σ it is found that there is hardening for transverse acoustic phonon on small wave vector zone (nearby point Γ), there is softening for transverse acoustic phonon on the softening zone and there is hardening for transverse acoustic phonon near point M. On line Δ it is found there is no softening and hardening for transverse acoustic phonon. On line Z it is found that there is softening for transverse acoustic phonon on small wave vector zone (nearby point X) and there is hardening for transverse acoustic phonon nearby point M. The influences of various parameters on transverse acoustic phonon excitation are also explored and it is found that the coupling of the magnon–phonon and the spin wave stiffness constant play an important role for the softening of transverse acoustic phonon. 相似文献
997.
In a two orbital model, we formulate Jahn–Teller coupled charge density wave in one electron per lattice site limit. Softening of Jahn–Teller phonons corresponding to distortion modes Q2 or Q3 associated with perfect nesting of Fermi surface leads to this instability at low temperature. The gap equation for charge density wave state and its dependences on electron–lattice coupling are calculated explicitly when any one of the Jahn–Teller modes is excited cooperatively. We find that the Q2 distortion mode yields lowest free energy. Effect of electron–lattice interaction on collective mode, such as amplitude mode, is more pronounced when the excited mode is Q2. 相似文献
998.
Optical spectroscopy measurements of the congruent LiNbO3 (LN) single crystals, weakly doped with Er (0.1–0.3 wt%) and Er (0.3 wt%) and Yb (0.5 wt%), have been carried out. The shape of the optical absorption and additional absorption bands registered after γ-irradiation suggests the presence of Er3+ ion pairs. EPR investigations were performed for LN single crystal doped with Er (0.1 wt%). Unusual behaviour of the temperature dependence of the intensity and linewidth of the main EPR line—corresponding to the fine transition of evenEr3+—ions, is reported. The main EPR line appears to be a superposition of several paramagnetic centres originating from isolated evenEr3+ ions and evenEr3+–evenEr3+ pairs of ions. In low temperature region (below 20 K), the main EPR signal is dominated by signals arising from evenEr3+–evenEr3+ pairs of ions. The inverse intensity of the EPR line at low temperature region fulfils the Curie–Weiss law and enabled to determine the Curie–Weiss constant Θ=1.5±0.5 K. The positive sign of Θ suggests that the ferromagnetic interactions arise in the system of evenEr3+–evenEr3+ ion pairs in LN. Our results suggest that the distribution of Er ions in congruent LN is not homogeneous and Er impurity ions can form clusters in host lattice even in the case of weak erbium doping. 相似文献
999.
We suggest that the high-temperature superconductivity can be attributed to the director-roles of the van Hove singularity
between an electron-electron interaction and an electron-phonon interaction. The difference between the critical temperature
and the pairing temperature is presented, and the Fermi arc, the d-wave symmetry and the poor conductivity, etc., are discussed. In particular, the non-s-wave symmetry is predicted to have the highest T
c for superconductors.
相似文献
1000.
A radial inhomogeneous magnetic field produced by counter-propagating currents in anti-Helmholtz configuration coils has been
superimposed to a Penning trap. The confinement properties of electrons in such a trap have been studied experimentally. Without
the radial B-field we find a number of operating conditions where instabilities occur, arising from higher order contributions
to the quadrupolar trapping field. When we apply the radial field the trap properties remain essentially unchanged until the
strength of this field at the boundary of the electron cloud is of the same order as the homogeneous Penning field. Then a
sudden breakdown in the confinement appears. The experiments have been performed in low magnetic fields. The equations of
motions of the trapped particles can be cast in a dimensionless form and our results can be considered as independent of the
field strength.
Contribution was presented at the TCP06, Vancouver Island, 2006. 相似文献