87 research outputs found
Observing Majorana Bound States in p-wave Superconductors Using Noise Measurements in Tunneling Experiments
The zero-energy bound states at the edges or vortex cores of chiral p-wave
superconductors should behave like majorana fermions. We introduce a model
Hamiltonian that describes the tunnelling process when electrons are injected
into such states. Using a non-equilibrium green function formalism, we find
exact analytic expressions for the tunnelling current and noise and identify
experimental signatures of the majorana nature of the bound states to be found
in the shot noise. We discuss the results in the context of different candidate
materials that support triplet superconductivity. Experimental verification of
the majorana character of midgap states would have important implications for
the prospects of topological quantum computation.Comment: 4 pages, 1 figur
Time-Loop Formalism for Irreversible Quantum Problems: Steady State Transport in Junctions with Asymmetric Dynamics
Non-unitary quantum mechanics has been used in the past to study
irreversibility, dissipation and decay in a variety of physical systems. In
this letter, we propose a general scheme to deal with systems governed by
non-Hermitian Hamiltonians. We argue that the Schwinger-Keldysh formalism gives
a natural description for those problems. To elucidate the method, we study a
simple model inspired by mesoscopic physics --an asymmetric junction. The
system is governed by a non-Hermitian Hamiltonian which captures essential
aspects of irreversibility.Comment: 4 pages, 4 figure
Universal out-of-equilibrium Transport in Kondo-correlated quantum dots: Renormalized dual Fermions on the Keldysh contour
The nonlinear conductance of semiconductor heterostructures and single
molecule devices exhibiting Kondo physics has recently attracted attention. We
address the observed sample dependence of the measured steady state transport
coefficients by considering additional electronic contributions in the
effective low-energy model underlying these experiments that are absent in
particle-hole symmetric setups. A novel version of the superperturbation theory
of Hafermann et al. in terms of dual fermions is developed, which correctly
captures the low-temperature behavior. We compare our results with the measured
transport coefficients.Comment: 5 pages, 2 figure
Prediction of the capacitance lineshape in two-channel quantum dots
We propose a set-up to realize two-channel Kondo physics using quantum dots.
We discuss how the charge fluctuations on a small dot can be accessed by using
a system of two single electron transistors arranged in parallel. We derive a
microscopic Hamiltonian description of the set-up that allows us to make
connection with the two-channel Anderson model (of extended use in the context
of heavy-Fermion systems) and in turn make detailed predictions for the
differential capacitance of the dot. We find that its lineshape, which we
determined precisely, shows a robust behavior that should be experimentally
verifiable.Comment: 4 pages, 3 figure
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