Josephson结中激发孤子的电泳脉冲方法—原理与数值实验

根据反射射理论讨论了电泳脉冲法产生磁通孤子的阈值条件。对甚长结作的数值实验与理论符合很好。对有限结，考虑到边界效应，电流台阶范围等因素，对孤子激发条件有额外的要求。对圆对称环域结用脉冲法激发了孤子，并分析了其中回波效应、外磁场等对激发条件的影响。所有结果表明，电流脉冲法是在Ｊｏｓｅｐｈｓｏｎ结中激发孤子态的有效方法，理论阈值条件可以提供有益的参考作用。     

Electronic Raman Scattering in Graphene

Linear dispersion near the Dirac points in the band structure of graphenes can give rise to novel physical properties. We calculate the electronic contribution to the Raman spectra in graphenes, which also shows novel features. In the clean limit, the Raman spectrum in the undoped graphene is linear （with a universal slope against impurity scattering） at low energy due to the linear dispersion near the Dirae points, and it peaks at a position corresponding to the van Hove singularity in the band structure. In a doped graphene, the electronic Raman absorption is forbidden up to a vertical inter-band particle-hole gap. Beyond the gap the spectrum follows the undoped case. In the presence of impurities, absorption within the gap （in the otherwise clean case） is induced, which is identified as the intra-band contribution. The Drude-like intra-band contribution is seen to be comparable to the higher energy inter-band Raman peak. The results are discussed in connection to experiments.     

sine-Gordon模型中旋转对称孤子解的动力学及其在大面积Josephson结方面的应用

用集体坐标和拉格朗日变分原理为基础的微扰论处理了n+1维旋转对称的sine-Gordon孤子在远离原点处受微扰势作用下的行为。强调孤子的粒子性并从正则方法导出其依赖于位置的广义动量和运动方程。这一方法可以处理一类相当广泛的微扰势而无需其具体形式即可定性地讨论孤子的行为。在无耗散条件下,研究了孤子的速度-位置相空间的特性,分析了诸如回波效应、不稳定不动点和逃逸等各种可能的现象。引入耗散后,得到了修正的运动方程。还讨论了上述结果在大面积Josephson结方面的应用,并与数值计算的结果作了比较,两者符合较好。     

Fingerprints of Mott Superconductivity

We improve a previous theory of doped Mort insulators with duality between pairing and magnetism by a further duality transform. As the result we obtained a quantum Ginzburg-Landau theory describing the Cooper pair condensate and the dual of spin condensate. We address the superconductivity by doping a Mort insulator,which we call the Mort superconductivity. Some fingerprints of such novelty in cuprates are the scaling between neutron resonance energy and superfluid density, and the induced quantized spin moment by vortices or Zn impurity (together with circulating charge super-current to be checked by experiments).     

Superconductivity,Pair Density Wave,and Neel Order in Cuprates

We investigate in underdoped cuprates possible coexistence of the superconducting order at zero momentum and pair density wave(PDW)at momentum Q=(Л,Л)in the presence of a Neel order.By symmetry,the d-wave uniform singlet pairing dS0 can coexist with the d-wave triplet PDW dTq,and the p-wave singlet PDW pSq can coexist with the p-wave uniform triplet pT0.At half filling,we find that the novel pSq+pT0 state is energetically more favorable than the dS0+dTQ state.At finite doping,however,the dS0+dTq state is more favorable.In both types of states,the variational triplet parameters cITq and pT0 are of secondary significance.Our results point to a fully symmetric Z2 quantum spin liquid with spinon Fermi surface in proximity to the Neel order at zero doping,which may not be adiabatically connected to the d-wave singlet superconductivity at finite doping with intertwining d-wave triplet PDW fluctuations and spin moment fluctuations.The results are obtained by variational quantum Monte Carlo simulations.     

环形Josephson结中圆对称孤子解的微扰分析

本文用微扰方法,研究环形Josephson结中有扰动情形下sine-Gordon方程的圆对称孤子解,得到孤子的动力学方程的解析形式。所得的I—V曲线(第一零场台阶)与数值计算结果符合得很好。 关键词：     

Realizing Majorana fermion modes in the Kitaev model

We study the possibility to realize a Majorana zero mode that is robust and may be easily manipulated for braiding in quantum computing in the ground state of the Kitaev model in this work. To achieve this we first apply a uniform [111] magnetic field to the gapless Kitaev model and turn the Kitaev model to an effective p+ip topological superconductor of spinons. We then study possible vortex binding in such system to a topologically trivial spot in the ground state. We consider two cases in the system: one is a vacancy and the other is a fully polarized spin. We show that in both cases, the system binds a vortex with the defect and a robust Majorana zero mode in the ground state at a weak uniform [111] magnetic field. The distribution and asymptotic behavior of these Majorana zero modes are studied. The Majorana zero modes in both cases decay exponentially in space, and are robust against local perturbations and other Majorana zero modes far away, which makes them promising candidates for braiding in topological quantum computing.     

CCl4,CH2Cl2和CHCl3对磷脂酰胆碱紫外电子吸收光谱的影响

测量了ＣＣｌ₄，ＣＨ₂Ｃｌ₂和ＣＨＣｌ₃对生物膜中磷脂酰胆碱作用的紫外电子吸收光谱，实验结果表明，由于ＣＣｌ₄，ＣＨ₂Ｃｌ₂和ＣＨＣｌ₃分子结构的差异，三种溶剂的极性依次递增，磷脂酰胆碱π－π^*电子跃迁的吸收峰红移。磷脂酰胆碱在ＣＣｌ₄中光谱呈单吸收峰，在ＣＨ₂Ｃｌ₂和ＣＨＣｌ₃中光谱特征呈双蜂结构，存在聚集体的激子态跃迁，由此给出了脂质分子聚集状态的光谱依据。 关键词：     

Josephson结中激发孤子的电流脉冲方法──原理与数值实验

根据反散射理论讨论了电流脉冲法产生磁通孤子的阈值条件。对甚长结作的数值实验与理论符合很好。对有限结，考虑到边界效应，电流台阶范围等因素，对孤子激发条件有额外的要求，对圆对称环域结用脉冲法激发了孤子，并分析了其中回波效应、外磁场等对激发条件的影响。所有结果表明，电流脉冲法是在Ｊｏｓｅｐｈｓｏｎ结中激发孤子态的有效方法，理论阈值条件可以提供有益的参考作用。