Non-damped Acoustic Plasmon and Superconductivity in Single Wall Carbon Nanotubes

We show that non-damped acoustic plasmons exist in single wall carbon nanotubes (SWCNT) and propose that the non-damped acoustic plasmons may mediate electron-electron attraction and result in superconductivity in the SWCNT. The superconducting transition temperature Tc for the SWCNT (3,3) obtained by this mechanism agrees with the recent experimental result (Z. K. Tang et al, Science 292, 2462(2001)). We also show that it is possible to get higher Tc up to 99 K by doping the SWCNT (5,5).Comment: REVTEX, 4 pages including 2 figures, Corrected typo

Dark Soliton Excitations in Single Wall Carbon Nanotubes

Dark soliton excitations are shown to exist in single wall carbon nanotubes (SWCNTs). At first, the nonlinear effective interatomic potential and the difference equation for longitudinal lattice displacement are obtained for the SWCNTs by expanding Brenner's many-body potential in a Taylor series up to fourth-order terms. Then using a multi-scale method, for short wavelength lattice excitations the equation of motion of lattice is reduced to the cubic nonlinear Schrodinger equation. Finally, the dark soliton solutions and relevant excitations in the SWCNTs with subsonic velocity are discussed.Comment: 11pages, no figure

The noncommutative QED threshold energy versus the optimum collision energy

Moller Scattering and Bhabha Scattering on noncommutative space-time is restudied. It is shown that the noncommutative correction of scattering cross sections is not monotonous enhancement with the total energy of colliding electrons, there is an optimum collision energy to get the greatest noncommutative correction. Most surprisingly, there is a linear relation between the noncommutative QED threshold energy and the optimum collision energy.Comment: 11 pages, 7 figures,Latex2e, Changed conten

Bound on Noncommutative Standard Model with Hybrid Gauge Transformation via Lepton Flavor Conserving ZZ Decay

The $Z\rightarrow e^{+}e^{-}$ decay is studied basing on the noncommutative standard model (NCSM) with the hybrid gauge transformation. It is shown that if the latter is not included, the noncommutative correction to the amplitude of the $Z\rightarrow e^{+}e^{-}$ appears only as a phase factor, so that there is no new physical effect on the decay width. However, when the hybrid gauge transformation is included, the noncommutative effect appears in the two-body decay process. The discrepancy between the experimental branch ratio and the standard model prediction allows us to set the bound on the noncommutative parameters.Comment: 9 pages, 3 figure

Noncommutative QED corrections to process e+e−→μ+μ−γe^+e^-\to\mu^+\mu^-\gamma at linear collider energies

The cross section for process $e^+e^-\to\mu^+\mu^-\gamma$ in the framework of noncommutative quantum electrodynamics(NC QED) is studied. It is shown that the NC correction of scattering sections is not monotonous enhancement with total energy of colliding electrons, but there is an optimal collision energy to get the greatest NC correction. Moreover, there is a linear relation between NC QED scale energy and the optimal collision energy. The experimental methods to improve the precision of determining NC effects are discussed, because this process is an ${\cal O}(\alpha^3)$ NC QED process, high precision tests are necessary.Comment: 15 pages, 6 figure

Constructing unextendible product bases from the old ones

We studied the construction problem of the unextendible product basis (UPB). We mainly give a method to construct a UPB of a quantum system through the UPBs of its subsystem. Using this method and the UPBs which are known for us, we construct different kinds of UPBs in general bipartite quantum system. Then we use these UPBs to construct a family of UPBs in multipartite quantum system. The UPBs can be used to construct the bound entangled states with different ranks.Comment: 6 pages, 1 figure

Nonlocality of orthogonal product basis quantum states

We study the local indistinguishability of mutually orthogonal product basis quantum states in the high-dimensional quantum system. In the quantum system of $\mathbb{C}^d\otimes\mathbb{C}^d$, where $d$ is odd, Zhang \emph{et al} have constructed $d^2$ orthogonal product basis quantum states which are locally indistinguishable in [Phys. Rev. A. {\bf 90}, 022313(2014)]. We find a subset contains with $6d-9$ orthogonal product states which are still locally indistinguishable. Then we generalize our method to arbitrary bipartite quantum system $\mathbb{C}^m\otimes\mathbb{C}^n$. We present a small set with only $3(m+n)-9$ orthogonal product states and prove these states are LOCC indistinguishable. Even though these $3(m+n)-9$ product states are LOCC indistinguishable, they can be distinguished by separable measurements. This shows that separable operations are strictly stronger than the local operations and classical communication.Comment: 5 page

The local distinguishability of any three generalized Bell states

We study the problem of distinguishing maximally entangled quantum states by using local operations and classical communication (LOCC). A question of fundamental interest is whether any three maximally entangled states in $\mathbb{C}^d\otimes\mathbb{C}^d (d\geq 4)$ are distinguishable by LOCC. In this paper, we restrict ourselves to consider the generalized Bell states. And we prove that any three generalized Bell states in $\mathbb{C}^d\otimes\mathbb{C}^d (d\geq 4)$ are locally distinguishable.Comment: 11 pages, 1 figure, accepted by Quantum Information Processin

The local unitary equivalence of multipartite pure states

In this paper, we give a method for the local unitary equivalent problem which is more efficient than that was proposed by Bin Liu $et \ al$ \cite{bliu}.Comment: Accepted by International Journal of Theoretical Physic

dd locally indistinguishable maximally entangled states in Cd⊗Cd\mathbb{C}^d\otimes\mathbb{C}^d

We give a explicit construction of $d$ locally indistinguishable orthogonal maximally entangled states in $\mathbb{C}^d\otimes\mathbb{C}^d$ for any $d\geq 4$. This gives an answer to the conjecture proposed by S. Bandyopadhyay in 2009. Thus it reflects the nonlocality of the fundamental feature of quantum mechanics.Comment: The paper is rewrited, especally the introduction. 5 pages, no figure