Spin-orbit effects in armchair carbon nanotubes: analytical results

Energy spectra and transport properties of armchair nanotubes with curvature induced spin-orbit interaction are investigated thoroughly. The spin-orbit interaction consists of two terms: the first one preserves the spin symmetry in rotating frame, while the second one breaks it. It is found that the both terms are equally important: i)at scattering on the potential step which mimics a long-range potential in the nanotubes; ii)at transport via nanotube quantum dots. It is shown that an armchair nanotube with the first spin-orbit term works as an ideal spin-filter, while the second term produces a parasitic inductance.Comment: 11 pages, 10 figure

Spin control in semiconductor quantum wires

We show that spin-flip rotation in a semiconductor quantum wire, caused by the Rashba and the Dresselhaus interactions (both of arbitrary strengths), can be suppressed by dint of an in-plane magnetic field. We found a new type of symmetry, which arises at a particular set of intensity and orientation of the magnetic field and explains this suppression. Based on our findings, we propose a transport experiment to measure the strengths of the Rashba and the Dresselhaus interactions.Comment: 4 pages, 4 figure

Integral representation of the RPA correlation energy

Using the spectral function F'(z)/F(z) the RPA correlation energy and other properties of a finite system can be written as a contour integral in a compact way. This yields a transparent expression and reduces drastically the numerical efforts for obtaining reliable values. The method applied to pairing vibrations in rotating nuclei as an illustrative example.Comment: 9 pages, 2 figures (eps files

Analysis of nucleus-nucleus collisions at high energies and Random Matrix Theory

We propose a novel statistical approach to the analysis of experimental data obtained in nucleus-nucleus collisions at high energies which borrows from methods developed within the context of Random Matrix Theory. It is applied to the detection of correlations in momentum distributions of emitted particles. We find good agreement between the results obtained in this way and a standard analysis based on the method of effective mass spectra and two-pair correlation function often used in high energy physics. The method introduced here is free from unwanted background contributions.Comment: 11 pages, 10 figure

Shell Structures and Chaos in Deformed Nuclei and Large Metallic Clusters

A reflection-asymmetric deformed oscillator potential is analysed from the classical and quantum mechanical point of view. The connection between occurrence of shell structures and classical periodic orbits is studied using the ''removal of resonances method'' in a classical analysis. In this approximation, the effective single particle potential becomes separable and the frequencies of the classical trajectories are easily determined. It turns out that the winding numbers calculated in this way are in good agreement with the ones found from the corresponding quantum mechanical spectrum using the particle number dependence of the fluctuating part of the total energy. When the octupole term is switched on it is found that prolate shapes are stable against chaos whereas spherical and oblate cases become chaotic. An attempt is made to explain this difference in the quantum mechanical context by looking at the distribution of exceptional points which results from the matrix structure of the respective Hamiltonians. In a similar way we analyse the modified Nilsson model and discuss its consequences for nuclei and metallic clusters.Comment: to appear in Physica Scripta., CNLS-94-02, a talk given at the Nobel sponsored conference SELMA 94 "New Nuclear Phenomena in the Vicinity of Closed Shell" (Stockholm and Uppsala, 29 Aug.- 3 Sept. 1994

Tri-axial Octupole Deformations and Shell Structure

Manifestations of pronounced shell effects are discovered when adding nonaxial octupole deformations to a harmonic oscillator model. The degeneracies of the quantum spectra are in a good agreement with the corresponding main periodic orbits and winding number ratios which are found by classical analysis.Comment: 10 pages, Latex, 4 postscript figures, to appear in JETP Letter

Anisotropic universal conductance fluctuations in disordered quantum wires with Rashba and Dresselhaus spin-orbit interaction and applied in-plane magnetic field

We investigate the transport properties of narrow quantum wires realized in disordered two-dimensional electron gases in the presence of k-linear Rashba and Dresselhaus spin-orbit interaction (SOI), and an applied in-plane magnetic field. Building on previous work [Scheid, et al., PRL 101, 266401 (2008)], we find that in addition to the conductance, the universal conductance fluctuations also feature anisotropy with respect to the magnetic field direction. This anisotropy can be explained solely from the symmetries exhibited by the Hamiltonian as well as the relative strengths of the Rashba and Dresselhaus spin orbit interaction and thus can be utilized to detect this ratio from purely electrical measurements.Comment: 10 pages, 4 figures, 1 tabl