Hi Abhishek, Your logic is correct, however there's an extra complication. Usually Delta is a small parameter, which leads to the dispersion changing only very slowly with the energy. However here Delta is relatively large, and as you calculate conductance for different energies, new modes may open. So in order to recover the correct BTK limit, you need to also change Delta=0.01 instead of 0.1, and energies=[0.0002 * i for i in xrange(100)] (so also 10x smaller energy range). Then you recover the familiar picture of a perfectly transmitting Andreev mode. Best, Anton On Wed, Jul 1, 2015 at 8:27 PM, abhishek kumar <abhinet08@gmail.com> wrote:

Hello,

I have been trying to understand conductance for Normal metal-superconductor (NS) proximity system numerically. The provided code is for tunneling conductance where we have the insulating barrier present at the junction. I am trying to reproduce the results for ideal NS junction (no barrier) where we expect a constant subgap conductance of value 2 (in units of e^2/h, ignoring spin degrees of freedom). Well... I am directly replacing the value of "barrier" in the code by zero and expect to get the correct result but it is not so. What am I missing here?

Also, if I want to get the conductance of NS junction for single channel case, what difference should I expect from multichannel case? Isn't width of the system (W) playing the role of number of channels?

Regards Abhishek Kumar Department of Physical Sciences University of Florida, Gainesville FL 32608 Alternate e-mail ID - kumarabhi@ufl.edu

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