This repository contains code related to entanglement entropy calculations in lattice gauge theory.

Programs:

calculates and plots the entanglement entropy of physical states of the form a|--> + b|++> in a 2-plaquette Z₂ lattice gauge theory. It also plots the EE using a link-based splitting of the space in which the right plaquette belongs to one region and the remaining links to its complement.
The basic result is fairly boring: the physical EE varies as it would in a 2-spin state, while the link EE is constant:

Usage

You need a recent version of Java and Apache Ant.

To compile the code, run ant jar in the main directory. This should produce lib/ee.jar. To run tests:

cd bin
./runtests

To run link-vs-phys-ee:

cd bin
./link-vs-phys-ee

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