This code was used to calculate the concurrence in https://arxiv.org/pdf/1612.08265.pdf

Usage example in src/runQuantumAnnealing.cpp.

Get the code with:

git clone --recursive https://github.com/qacwnfq/phaseTransitionsAndConcurrence/

Compiling QuantumAnnealing.cpp (needs compiler which can compile c++11 standard):

cd src/
make
./runQuantumAnnealing.out

Run the boost unit tests:

This is optional, but useful for CI. Install the library on UBUNTU with sudo apt-get install libboost-test-dev. Travis-CI automatically executes the tests and complains if they fail.

cd tests/
make
./test_QuantumAnnealing.out

The magnetization.cpp script calculates the free energy and the magnetization of the systen in x- and z-direction. It can be compiled with:

g++ -std=c++14 src/magnetization.cpp -O3

QuantumAnnealing.py contains additional functions useful for analysis, like calculating the concurrence in the classical limit.