Anomalous density of states of a Luttinger liquid in contact with a superconductor

We study the frequency and space dependence of the local tunneling density of states of a Luttinger liquid (LL) which is connected to a superconductor. This coupling {\em strongly} modifies the single-particle properties of the LL. It significantly enhances the density of states near the Fermi level, whereas this quantity vanishes as a power law for an isolated LL. The enhancement is due to the interplay between electron-electron interactions and multiple back-scattering processes of low-energy electrons at the interface between the LL and the superconductor. This anomalous behavior extends over large distances from the interface and may be detected by coupling normal probes to the system.Comment: 8 pages Revtex, two postscript figure

Josephson π\pi-state in superconductor-Luttinger liquid hybrid systems

Josephson current through a Luttinger liquid (LL) under a magnetic field is theoretically studied. We derive an analytical expression of Josephson current for clean interfaces, by using quasiclassical Green's function and functional bosonization procedure. We show that critical currents can be renormalized by electron-electron interactions at perfect transparency when LL is adiabatically connected with superconductors. We also find that a generation of $\pi$-state, due to spin-dependent energy shift in Andreev bound states (ABS), is prohibited even at zero temperature when the strength of repulsive interactions reaches some critical value. The suppression of $\pi$-state is caused by the low energy fluctuations propagating in LL, and making the Zeeman splitting in ABS blurred.Comment: 5 pages, 4figure

DC Josephson Effect in a Tomonaga-Luttinger Liquid

The dc Josephson effect in a one-dimensional Tomonaga-Luttinger (TL) liquid is studied on the basis of two bosonized models. We first consider a TL liquid sandwiched between two superconductors with a strong barrier at each interface. Both the interfaces are assumed to be perfect if the barrier potential is absent. We next consider a TL liquid with open boundaries, weakly coupled with two superconductors. Without putting strong barriers, we instead assume that the coupling at each interface is described by a tunnel junction. We calculate the Josephson current in each model, and find that the two models yield same results. The Josephson current is suppressed by repulsive electron-electron interactions. It is shown that the suppression is characterized by only the correlation exponent for the charge degrees of freedom. This result is inconsistent with a previously reported result, where the spin degrees of freedom also affects the suppression. The reason of this inconsistency is discussed.Comment: 18 page

User-centered design and evaluation of an integrated AR-VR system for tele-maintenance

In case of undocumented machine failures on-site maintenance personnel can cooperate with a remote expert using telecommunication equipment. We present a new concept for a maintenance system which provides a synchronous shared visual workspace even when only limited bandwidth is available. A mechanic uses an Augmented Reality (AR) system which is connected to the Virtual Reality (VR) system of a remote expert. The expert interactively creates 3D instructions on his VR system that are displayed on a hand-held tablet computer of the mechanic. The mechanic considers these instructions during his maintenance work but can also interact with the live AR view to create spatial references for the expert. The system was evaluated by 18 experienced automobile mechanics. The maintenance task consisted of the disassembly of the camshaft housing of an internal combustion engine. The results show that participants completed more tasks and used less verbal instructions when using the VR system compared to a video system

Anomalous density of states of a Luttinger liquid in contact with a superconductor

We study the frequency and space dependence of the local tunneling density of states of a Luttinger liquid (LL) which is connected to a superconductor. This coupling strongly modifies the single-particle properties of the LL. It significantly enhances the density of states near the Fermi level, whereas this quantity vanishes as a power law for an isolated LL. The enhancement is due to the interplay between electron-electron interactions and multiple back-scattering processes of low-energy electrons at the interface between the LL and the superconductor. This anomalous behavior extends over large distances from the interface and may be detected by coupling normal probes to the system