Hello Anton,
thank you a lot for your quick reply. So I had a false expectation about the PHS. The paper is actually helpful to me and solves my understanding problem. Best, Richard ________________________________ From: Anton Akhmerov <anton.akhmerov...@gmail.com> Sent: Wednesday, February 17, 2021 9:12:55 AM To: Richard Gerhard Hess Cc: kwant-discuss@python.org Subject: Re: [Kwant] Question: PHS symmetry of conductance in NS junctions Hi Richard, Andreev conductivity isn't expected to be symmetric outside of the gap, so that's correct. For a related discussion check out https://arxiv.org/abs/1905.05438 Best, Anton On Tue, 16 Feb 2021 at 10:32, Richard Gerhard Hess <richardgerhard.h...@unibas.ch> wrote: > > Dear all, > > > I have a question regarding the conductance in normal-superconductor > junctions. I expect the conductance to be particle-hole symmetric, since the > scattering region and the leads obey PHS. However, downloading the tutorial > 2.6 and extending the energy interval, for which the conductance is > calculated, to negative values, results in a not particle-hole symmetric > conductance spectrum above the gap. The conductance takes larger values for > positive energies above the gap. Removing the superconducting lead and > choosing a long superconducting section leads to the same sub-gap > conductance. This was already discussed in the Kwant forum and makes sense to > me. However, in this setup I observe a symmetric spectrum for large energies. > The conductance for negative and positive energies agree. What is reason for > this behaviour? > > > The code "3_advanced_concepts", which was shared in the recent Kwant > workshop, gives the same result. I mean the Majorana part and not the > topological insulator example. This effect of broken PHS is strongly > pronounced near the topological phase transition, since the gap closes. If I > consider a NSN junction, then I observe even not particle hole symmetric sub > gap states: The sub-gap states are at the same bias but do not have always > the same peak height in the conductance. > > > > Why does this happen? Maybe it is obvious, but I can not see it right now. > The PHS is not broken! What I am missing here and what is the physical > explanation? > > > Best regards, > > Richard > >
