共查询到20条相似文献,搜索用时 15 毫秒
1.
Multi-mode cavities have now attracted much attention both experimentally and theoretically. In this paper, inspired by recent experiments of cavity-assisted Raman transitions, we realize a two-axis spin Hamiltonian H = q(J_x~2+ χJ_y~2) + ω_0J_z in two cavities. This realized Hamiltonian has a distinct property that all parameters can be tuned independently. For proper parameters, the well-studied one- and two-axis twisting Hamiltonians are recovered, and the scaling of N~(-1) of the maximal squeezing factor can occur naturally. On the other hand, in the two-axis twisting Hamiltonian, spin squeezing is usually reduced when increasing the atomic resonant frequency ω_0. Surprisingly, we find that by combining with the dimensionless parameter χ(-1), this atomic resonant frequency ω_0 can enhance spin squeezing greatly. These results are beneficial for achieving the required spin squeezing in experiments. 相似文献
2.
In this paper,the variable separation approach is used to obtain localized coherent structures of the (2 1)-dimensional generalized Davey-Stewarson equations:iqt 1/2(qxx=qyy) (R S)q=0,Rx=-σ/2|q|y^2,Sy=-σ/2|q|2/x.Applying a special Baecklund transformation and introducing arbitrary functions of the seed solutions.and abundance of the localized structures of this model is derived,By selceting the arbitrary functions appropriately,some special types of localized excitations such as dromions,dromion lattice,breathers,and instantons are constructed. 相似文献
3.
The commutation relations of thegenerators of the two-parameter deformed quantum algebra SUq,s(4) are given and irreducible q,s-tensor operators of rank (1/2) of the quantum algebra SUq,s(2) are constructed. 相似文献
4.
利用考虑Davidson修正的内收缩多参考组态相互作用(icMRCI+Q)方法结合相关一致基组aug-ccpV6Z计算了AlH~+离子前两个离解极限对应的5个Λ-S态和10个?态的势能曲线.为了提高势能曲线的可靠性和精确性,计算中考虑了自旋轨道耦合效应、芯电子价电子相关和标量相对论修正以及将势能外推至完全基组极限.基于得到的势能曲线,获得了束缚和准束缚的4个Λ-S态和8个?态的光谱常数和振动能级,与已有的实验结果符合.计算了2(1/2)→X~2Σ_(1/2)~+和A~2Π_(3/2)→X~2Σ_(1/2)~+跃迁的跃迁偶极距.利用计算的精确的势能曲线和跃迁偶极矩,获得了2(1/2)~(第一势阱)(υ′=0, 1)→X~2Σ_(1/2)~+(υ′′)和A~2Π_(3/2)(υ′=0, 1)→X~2Σ_(1/2)~+(υ′′)跃迁的高度对角化分布的Franck-Condon因子(f_(00)和f_(11))和大的振动分支比;预测了2(1/2)~(第一势阱)(υ′=0, 1)和A~2Π_(3/2)(υ′=0, 1)态短的自发辐射寿命和窄的辐射宽度,这适合于AlH~+离子的快速激光致冷.所需的3束激光冷却波长都在紫外区域.这些结果表明了激光冷却AlH~+离子的可行性.此外,评估了自旋轨道耦合效应对光谱常数、振动能级和激光冷却AlH~+离子的影响. 相似文献
5.
Recently, there have been great interest and advancement in the field of laser cooling and magneto-optical trapping of molecules. The rich internal structure of molecules naturally lends themselves to extensive and exciting applications. In this paper, the radical~(138)Ba~(19) F, as a promising candidate for laser cooling and magneto-optical trapping, is discussed in detail.The highly diagonal Franck–Condon factors between the X~2Σ~+_(1/2)and A~2Π_(1/2) states are first confirmed with three different methods. Afterwards, with the effective Hamiltonian approach and irreducible tensor theory, the hyperfine structure of the X~2Σ~+_(1/2)state is calculated accurately. A scheme for laser cooling is given clearly. Besides, the Zeeman effects of the upper(A~2Π_(1/2)) and lower(X~2Σ~+_(1/2)) levels are also studied, and their respective g factors are obtained under a weak magnetic field.Its large g factor of the upper state A~2Π_(1/2) is advantageous for magneto-optical trapping. Finally, by studying Stark effect of Ba F in the X~2Σ~+_(1/2), we investigate the dependence of the internal effective electric field on the applied electric field. It is suggested that such a laser-cooled Ba F is also a promising candidate for precision measurement of electron electric dipole moment. 相似文献
6.
FAN Hong-Yi YAN Peng 《理论物理通讯》2007,48(3):428-430
By virtue of the technique of integration within an ordered product of operators, we derive the normal ordering expansion of a one- and two-mode combination squeezing operator for two harmonic oscillators with coordinate- momentum coupling. It turns out that this squeezing operator just diagonalizes the Hamiltonian H=p^21/2m1+m1ω^21x^21/2+p^222m2+m2ω^22x^22/2-λx2p1 so its ground state is a one- and two-mode combination squeezed state. Quantum fluctuation in the ground state is calculated. 相似文献
7.
The quantum Euclidean space
RqN is a kind of
noncommutative space that is obtained from ordinary Euclidean space
RN by deformation with parameter q. When N is odd, the
structure of this space is similar to
Rq3. Motivated by
realization of Rq3 by differential operators in
R3, we give such realization for Rq5 and
Rq7 cases and generalize our results to
RqN (N odd) in this paper, that is, we show that the
algebra of RqN can be realized by differential operators
acting on C∝ functions on undeformed space
RN. 相似文献
8.
D. Arnal 《Journal of Geometry and Physics》1987,4(4):439-467
Let
be a finite dimensional real Lie algebra and
* its dual.
* is a Poisson manifold. Thus the space C∞(
*) of C∞ functions on
* has an associative and a Lie algebra structure. The problem of formal deformations of such a structure needs the determination of some cohomology groups of C∞(
*), considered as a module on itself for left multiplication or adjoint representation. We determine here these groups. The result is very similar to the case of C∞(W), where W is a symplectic manifold except for the Lie algebras hr ×
m, direct products of Heisenberg and abelian Lie algebras. 相似文献
9.
10.
According to the Riemann-Roch theorem, we construct bases H-n(i) and N-m(f), for the meromorphic λ = -1 and λ = -1/2 differentials on the Riemann sphere S2. The dual bases, A-n(i), and D-m(j), of these meromorphic λ differentials on Cr curves are defined. Expanding the component fields TB(z) and TF(z) of the stress-energy tensor T(z) in the superconformal field theory by the dual bases A-n(i), and D-m(j), respectively, we obtain a series of expanding coefficients. The commutation relations among these coefficients are given explicitly, which,is just the multi-pole Neveu-Schwarz algebra with central extensions on the Riemann supersphere S. Physical implics tions of the algebra are also discussed. 相似文献
11.
Shahn MajidM. J. Rodríguez-Plaza 《Journal of Geometry and Physics》1993,11(1-4):437-443
We describe the quasitriangular structure (universal R-matrix) on the nonstandard quantum group Uq(H1, H2, X±) associated to the Alexander-Conway matrix solution of the Yang-Baxter equation. We show that this Hopf algebra is connected with the super-Hopf algebra Uqgl(1 | 1) by a general process of superization. 相似文献
12.
The π0 spectrum in the KL0 → 3π decay was measured using a wire chambers magnetic spectrometer. In the usual approximation, the matrix element can be expressed as: M2 ≈ 1 + 2a0(MK/Mπ2)(2Tπ0−Tπ0max) + a1(MK2/Mπ4)(2Tπ0−Tπ0max)2. We obtained a0 = −0.282 ± 0.011 and a1 consistent with zero. 相似文献
13.
We calculate the CP averaged branching ratios and CP-violating asymmetries for Bs^0 → η'η' and η'η' decays in the perturbative QCD (pQCD) approach here. The pQCD predictions for the C P-averaged branching ratios are Br(Bs^0 → ηη)=(14.2-7.5^+18.0) ×10^-6,Br(Bs^0 → ηη')=(12.4-7.0^+18.2)×10^-6,and Br(Bs^0 → η'η') =(9.2-4.9^+15.3)×10^-6, which agree well with those obtained by employing the QCD factorization approach and also be consistent with available experimental upper limits. The gluonic contributions are small in size: less than 7% for Bs →ηηand ηη' decays, and around 18% for Bs →η'η' decay. The CP-violating asymmetries for three decays are very small: less than 3% in magnitude. 相似文献
14.
The difference of τB and τAb indicates the role of the light flavors,We calculate the lifetinmes of B-meson and Λb based on the weak effective Hamiltonian while assuming the heavy baryon is constructed by a heavy b-quark and a diquark containing two light quarks.In this scenario,we use the information of the measured ratio τΛb/τB as input to predict rates of the inclusive weak decays of ∑b^(*) and Ξb^(*) into non-bottom final states.We find that these rates of ∑b^(*) and Ξb^(*) are much larger than those of B-mesons and Λb,We also give the predictions for the lifetimes of Ωb and Ω,Pheomenological implication of our result is discussed. 相似文献
15.
采用化学沉淀法一次煅烧工艺制备了Ba1.99-x/2-2ySiO4:Eu0.012+, Lix+y2+, Euy3+绿色荧光粉, 用X射线衍射仪和荧光分光光度计对样品的晶体结构、发光性能进行表征. 结果表明: 少量Eu2+, Li+和Er3+的共掺杂没有改变晶体结构; 其激发光谱分布在270–440 nm波长范围, 谱峰位于288 nm, 360 nm处, 可以被InGaN 管芯产生的360–410 nm辐射有效激发; 在360 nm近紫外光激发下, 测得其发射光谱峰值在500 nm 处, 是Eu2+4f65d1→4f7跃迁的典型发射; 荧光粉发光强度随着Li+掺杂量的增大先增强, 后减弱, 当x=0.1时, 发光强度最大; 随着Li+, Er3+共掺杂量的增加(y=0.012), 出现位于530 nm和488 nm的发射峰, 对应于Er3+的2H11/2→4I15/2和4F7/2→4I15/2特征发射, 同时分析了Eu2+→Er3+的能量传递过程.
关键词:
化学沉淀法
2SiO4:Eu2+,Li+,Er3+')" href="#">Ba2SiO4:Eu2+,Li+,Er3+
能量传递
发光性能 相似文献
16.
CaMoO4:Eu3+,Bi3+,Li+红色荧光粉的共沉淀制备与表征 总被引:1,自引:0,他引:1
采用共沉淀法合成了红色荧光粉Ca0.75MoO4:Eu0.253+、Ca0.75MoO4:Eu0.25-x3+,Bix3+及Ca0.5MoO4:Eu0.25-2x3+, Bix3+,Li0.25+x+,并采用X射线衍射(XRD)、拉曼光谱,扫描电镜(SEM)和荧光光谱(PL)测定分析了其结构形貌特征及发光性能。结果表明:制备的CaMoO4:Eu3+,Bi3+,Li+红色荧光粉为白钨矿结构,颗粒尺寸约为0.5~1 μm。掺杂Bi3+的Ca0.75MoO4:Eu0.25-x3+,Bix3+的相对发光强度明显高于未掺Bi3+的Ca0.75MoO4:Eu0.253+荧光粉。Bi3+离子的掺杂将吸收来的能量传递给激活离子Eu3+,起到了能量传递的作用。当Bi3+掺杂量为x=0.005时,在395 nm激发下,主发射峰在616 nm处的相对发光强度最大,但掺杂浓度过高时会出现浓度猝灭现象。另外,电荷补偿剂的掺入能够解决材料中因同晶取代引起的电荷不平衡的问题,以Li+作电荷补偿剂、Eu3+和 Bi3+共掺合成的Ca0.5MoO4:Eu3+0.23,Bi0.013+,Li+0.26红色荧光粉的发光性能强于Ca0.75MoO4:Eu0.253+、Ca0.5MoO4:Eu0.253+, Li0.25+及Ca0.75MoO4:Eu0.243+,Bi0.013+。 相似文献
17.
For deuteron's electromagnetic form factors, perturbative QCD (pQCD) predicts that G00+ becomes the dominate helicity amplitude and G+0+ and G+ -+ are suppressed by factors AQCD/Q and AQCD2/Q2 at large Q2 respectively. We try to discuss the higher-order corrections beyond the pQCD asymptotic predictions by interpolating an analytical form to the intermediate energy region. From fitting the data, our results show that the helicity-zero to zero matrix element G00+ dominates the gross structure function A(Q2) in both the large and intermediate energy regions. It is a good approximation for G+ -+ to ignore the higher-order contributions and the higher-order corrections to G+0+ should be taken into account due to sizeable contributions in the intermediate energy region. 相似文献
18.
利用发展的调制俘获损耗荧光光谱技术实验测量了超冷铯分子0u+(6P3/2)长程态的高灵敏光缔合光谱. 光谱探测范围较国际已有报道扩大了60 cm-1, 观察到25个长程区域新的振动能级. 通过LeRoy-Bernstein公式对振动束缚能数据进行拟合, 获得了超冷铯分子0u+(6P3/2)态的长程系数C3 为16.103±0.010. 构建了超冷铯分子0u+(6P3/2)态长程区域的势能曲线. 相似文献
19.
WANG Zhi-Gang 《理论物理通讯》2015,63(4):466-480
In this article, we calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion, and study the C γμ- Cγνtype scalar, axial-vector and tensor tetraquark states in details with the QCD sum rules. In calculations, we use the formula μ = (M 2X/ Y /Z-(2Mc)2)~(1/2) to determine the energy scales of the QCD spectral densities. The predictions MJ =2=(4.02+0.09-0.09) GeV, MJ =1=(4.02+0.07-0.08) GeV favor assigning the Zc(4020) and Zc(4025) as the JP C= 1+-or 2++diquark-antidiquark type tetraquark states, while the prediction M++J =0=(3.85+0.15-0.09) GeV disfavors assigning the Z(4050) and Z(4250) as the JP C= 0diquark-antidiquark type tetraquark states. Furthermore, we discuss the strong decays of the 0++, 1+-, 2++diquark-antidiquark type tetraquark states in details. 相似文献
20.
We study the mixing of pseudo-Goldstone bosons predicted by technicolor theory and the effects on HERA high-Q2 events. We find that: (a) there eyist two F = 0 scalar leptoquarks P3′ with m(P3′) = 200 GeV and P30 with m(30) =225 GeV for β1 = β2 = 0.4; (b) the P3′ and P30 can contribute the required cross section to account for the excesses of NC and CC high-Q2 events; (c) the coexistence of P3′ and P30 may be responsible for the splitting of averaged mass of the H1 and ZEUS high-Q2 neutral current events. 相似文献