Optimal purification of thermal graph states
Kay, A, Pachos, J K, Dür, W, Briegel, H J · CERN Document Server (European Organization for Nuclear Research) · 2006
In this paper, a purification protocol is presented and its performance is proven to be optimal when applied to a particular subset of graph states that are subject to local Z-noise. Such mixed states are produced when systems described by graph Hamiltonians are brought into thermal equilibrium. From the optimal protocol, one can derive the exact value of the critical temperature that corresponds to this Hamiltonian, as well as the the related optimal purification rates. A possible implementation of graph Hamiltonians is proposed, which requires only bipartite interactions and local magnetic fields, enabling the tuning of the critical temperature.