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王安民 《青海师范大学学报(自然科学版)》2003,(1):96-96
给出了等差数列的通项公式和前n项和公式是特殊的一次函数和二次函数的具体描述及几何意义,通过例题从几例的角度如何解有关等差数列的习题。 相似文献
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研究了Dzialoshinski-Moriya(DM)相互作用对由XXZ自旋链所形成热态的贝尔不等式违背的影响.结果表明DM相互作用和具有较大正值的各向异性参数可以增强贝尔不等式的违背并能够提高贝尔不等式违背的临界温度.通过贝尔不等式违背和热纠缠的对比,发现热纠缠的临界温度高于贝尔不等式违背的临界温度,这表明一些量子纠缠态不违背贝尔不等式. 相似文献
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It has been found that for a fixed degree of fuzziness in the coarsened references of measurements,the quantum-toclassical transition can be observed independent of the macroscopicity of the quantum state.We explore a general situation that the degree of fuzziness can change with the rotation angle between two states(different rotation angles represent different references).The fuzziness of reference comes from two kinds of fuzziness:the Hamiltonian(rotation frequency)and the timing(rotation time).For the fuzziness of the Hamiltonian alone,the degree of fuzziness for the reference will change with the rotation angle between two states,and the quantum effects can still be observed with any degree of fuzziness of Hamiltonian.For the fuzziness of timing,the degree of the coarsening reference is unchanged with the rotation angle.During the rotation of the measurement axis,the decoherence environment can also help the classical-to-quantum transition due to changing the direction of the measurement axis. 相似文献
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We investigate the effect of decoherence from a spin environment on the quantum channel capacity.Our results imply that the time evolution of the quantum channel capacity depends on the number of freedom degrees of the environment,the tunneling element,the initial state of the environment,and the system-environment coupling strength.From the analysis,we find that the strong tunneling elements and the weak coupling strength can enhance the quantum channel capacity while the environment with a large number of freedom degrees and the strong coupling strength will shrink it. 相似文献
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Second-harmonic generation in asymmetric quantum dots in the presence of a static magnetic field 下载免费PDF全文
The second-harmonic generation(SHG) coefficient in an asymmetric quantum dot(QD) with a static magnetic field is theoretically investigated.Within the framework of the effective-mass approximation,we obtain the confined wave functions and energies of electrons in the QD.We also obtain the SHG coefficient by the compact-density-matrix approach and the iterative method.The numerical results for the typical GaAs/AlGaAs QD show that the SHG coefficient depends strongly on the magnitude of magnetic field,parameters of the asymmetric potential and the radius of the QD.The resonant peak shifts with the magnetic field or the radius of the QD changing. 相似文献
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研究了DM(dzialoshinski-moriya)相互作用对一个处于非均匀磁场中的混合自旋链热纠缠的影响,发现尽管外磁场具有减少自旋链热纠缠的作用,但是DM相互作用能够把混合链的热纠缠增加到一个最大值;另外分析了磁场的非均匀性对混合自旋链热纠缠的影响.研究有助于理解DM对混合自旋链热纠缠的影响. 相似文献
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We extend the BCS paring model with equally spaced energy levels to a general one-dimensional spin-1/2 Heisenberg model The two well-known symmetries of the Heisenberg model, i.e. permutational and spin-inversion symmetries, no longer exist. However, when jointing these two operations together, we find a new symmetry of energy spectrum between its subspace n and subspace L - n of the Fock space. A rigorous proof is presented. 相似文献