Everybody-at-once entanglement swapping

[rdviii]

Hypothetically, with no purification, all of the intermediate nodes could swap asynchronously and essentially simultaneously. In fact, that's probably what we want, to minimize decoherence. But, the condition clause will have to be extended in order to support "when part of this connection" rather than "when entangled with this node" and you have to be careful of not creating the wrong result by accident. See swap_table ConnectionManager::EntanglementSwappingConfig(int swapper_address, std::vector path, std::vector<QNIC_pair_info> qnics, int num_resources){

[rdviii]

The tricky part of this is figuring out the classical messaging: should each swapper notify its neighbors, who then adjust the Pauli frame correction based on their own results and send on, or should each swapper notify the end nodes directly, in which case the end nodes have to total up all of the Pauli frame corrections?

In either case, if there are multiple E2E Bell pairs in process, one of the tricky parts is making sure you are tracking the right Bell pair.