2,094 research outputs found
Shiba impurity bound states as a probe of topological superconductivity and Fermion parity changing quantum phase transitions
Spin-orbit coupled superconductors are potentially interesting candidates for
realizing topological and potentially non-Abelian states with Majorana
Fermions. We argue that time-reversal broken spin-orbit coupled superconductors
generically can be characterized as having sub-gap states that are bound to
localized non-magnetic impurities. Such bound states, which are referred to as
Shiba states, can be detected as sharp resonances in the tunneling spectrum of
the spin-orbit coupled superconductors. The Shiba state resonance can be tuned
using a gate-voltage or a magnetic field from being at the edge of the gap at
zero magnetic fields to crossing zero energy when the Zeeman splitting is tuned
into the topological superconducting regime. The zero-crossing signifies a
Fermion parity changing first order quantum phase transition, which is
characterized by a Pfaffian topological invariant.
These zero-crossings of the impurity level can be used to locally
characterize the topological superconducting state from tunneling experiments.Comment: 5 pages; 3 figures: minor reference update
Stochastic Duality and Eigenfunctions
We start from the observation that, anytime two Markov generators share an eigenvalue, the function constructed from the product of the two eigenfunctions associated to this common eigenvalue is a duality function. We push further this observation and provide a full characterization of duality relations in terms of spectral decompositions of the generators for finite state space Markov processes. Moreover, we study and revisit some well-known instances of duality, such as Siegmund duality, and extract spectral information from it. Next, we use the same formalism to construct all duality functions for some solvable examples, i.e., processes for which the eigenfunctions of the generator are explicitly known
Diamagnetic susceptibility obtained from the six-vertex model and its implications for the high-temperature diamagnetic state of cuprate superconductors
We study the diamagnetism of the 6-vertex model with the arrows as directed
bond currents. To our knowledge, this is the first study of the diamagnetism of
this model. A special version of this model, called F model, describes the
thermal disordering transition of an orbital antiferromagnet, known as
d-density wave (DDW), a proposed state for the pseudogap phase of the high-Tc
cuprates. We find that the F model is strongly diamagnetic and the
susceptibility may diverge in the high temperature critical phase with power
law arrow correlations. These results may explain the surprising recent
observation of a diverging low-field diamagnetic susceptibility seen in some
optimally doped cuprates within the DDW model of the pseudogap phase.Comment: 4.5 pages, 2 figures, revised version accepted in Phys. Rev. Let
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