Entanglement purification without controlled-NOT gates by using the natural dynamics of spin chains
Koji Maruyama, Franco Nori · Physical Review A · 2008
We present a simple protocol to purify bipartite entanglement in spin-$1∕2$ particles by utilizing only natural spin-spin interactions, i.e., those that can commonly be realized in realistic physical systems and ${S}_{z}$ measurements on single spins. Even the standard isotropic Heisenberg interaction is shown to be sufficient to purify mixed state entanglement. Our protocol does not need controlled-NOT (CNOT) gates that are very hard to implement experimentally. This approach could be useful for quantum-information processing in solid-state-based systems.