Most of the methods that I have seen in various papers all take single examples and then proceed to manually perform swapping by re-writing the states on a different basis and then performing a measurement to swap entanglement.
Or entanglement is spoken about very briefly, such as in: Horodecki, R., Horodecki, P., Horodecki, M., & Horodecki, K. (2009). Quantum entanglement. Reviews of Modern Physics, 81(2), 865–942. - Page 12
I wish to code entanglement swapping for some arbitrary state of 4 qubits, of which A-B and C-D are entangled. I wish to perform the swapping leaving A-D entangled. How would I go about doing the same? I was unable to find any detailed resources on swapping or a generalized entanglement swapping procedure anywhere.