Quantum transport simulations made easy
=======================================

Kwant is a Python package for numerical calculations on tight-binding models
with a strong focus on quantum transport.  It is designed to be flexible, easy to
use, while not sacrificing performance.

Tight-binding models are ubiquitous in quantum physics and they can be found in a vast variety of
situations including graphene, quantum Hall effect, topological insulators, superconductivity, semi-conductors,
spintronics, molecular electronics, any combination of the above and many other cases. 
While all these systems have very distinct physics, their mathematical description is very close. 
Kwant has been designed so that their computer implementation is also very close: changing a few lines of code is all that is needed to go from one example to another.  

Kwant does not use the traditional ‘input' files often found in scientific softwares. Instead, one write small python
programs (benefiting from python simple and very powerful syntax) to "make" the sample and "measure" its quantum properties
(conductance, density of states, etc). Learning to use Kwant is very fast, no more than a couple of hours are needed to get started.
You can find how easy it is to use in practice by going through the `tutorial </docs/tutorial/>`_ or  Kwant main `article </paper>`_.

Kwant is provided to the physics community as an open source free software (we merely ask you to quote Kwant article in scientific publications where
Kwant was used). Below is a rapid survey of a few applications of Kwant.


conductance of a Corbino disk in a quantum Hall regime
------------------------------------------------------

Bla Bla

.. image:: collage.png
   :scale: 30%
   :target: collage.png



A piece of bilayer graphene lattice
-----------------------------------

* Density of states in a chaotic stadium billiard (middle)
* A quantum wire (gray) attached to a superconducting electrode (blue) give rise to a Majorana bound states
  which can be seen in the spectrum of the device (upper and lower right).


Flying qubit
------------

.. container:: leftside

   .. image:: flying-qubit.png

This example shows some numerical simulations (left) and experimental results (right) for a flying Qubit sample made in a
GaAs/GaAlAs heterostrucutre. See Yamamoto et al, Nature Nanotechnology 7, 247 (2012) for details about this experiment. 
(Simulations: T. Bautze et al. to be submitted to Phys. Rev. B). In this example, particular attention was paid to designing a realistic
model for the confining potential seen by the electrons so that rather subtle aspects of the experiments could be reproduce. Such type of
"numerical experiments" can not only be used to interpret the experimental data but also as an aid in designing the sample geometry or in the choice of
materials.