Meservey-Tedrow-Fulde effect in a quantum dot embedded between metallic and superconducting electrodes

Magnetic field applied to the quantum dot coupled between one metallic and one superconducting electrode can produce a similar effect as has been experimentally observed by Meservey, Tedrow and Fulde [Phys. Rev. Lett. 25, 1270 (1970)] for the planar normal metal -- superconductor junctions. We investigate the tunneling current and show that indeed the square root singularities of differential conductance exhibit the Zeeman splitting near the gap edge features V = +/- Delta/e. Since magnetic field affects also the in-gap states of quantum dot it furthermore imposes a hyperfine structure on the anomalous (subgap) Andreev current which has a crucial importance for a signature of the Kondo resonance.Comment: 7 pages, 8 figure

Lattice study on two-color QCD with six flavors of dynamical quarks

We study the dynamics of SU(2) gauge theory with NF=6 Dirac fermions by means of lattice simulation to investigate if they are appropriate to realization of electroweak symmetry breaking. The discrete analogue of beta function for the running coupling constant defined under the Schroedinger functional boundary condition are computed on the lattices up to linear size of L/a=24 and preclude the existence of infrared fixed point below 7.6. Gluonic observables such as heavy quark potential, string tension, Polyakov loop suggest that the target system is in the confining phase even in the massless quark limit.Comment: 7 pages, 9 figures, Proceedings of The 30th International Symposium on Lattice Field Theory, June 24-29, 2012, Cairns, Australi

Tunable Fermi-Edge Resonance in an Open Quantum Dot

Resonant tunneling in an open mesoscopic quantum dot is proposed as a vehicle to realize a tunable Fermi-edge resonance with variable coupling strength. We solve the x-ray edge problem for a generic nonseparable scatterer and apply it to describe tunneling in a quantum dot. The tunneling current power law exponent is linked to the S-matrix of the dot. The control of scattering by varying the dot shape and coupling to the leads allows to explore a wide range of exponents. Transport properties, such as weak localization, mesoscopic conductance fluctuations, and sensitivity to Wigner-Dyson ensemble type, have their replicas in the Fermi-edge singularity.Comment: 4 pages, 3 figure