2 research outputs found
Growth of graph states in quantum networks
We propose a scheme to distribute graph states over quantum networks in the
presence of noise in the channels and in the operations. The protocol can be
implemented efficiently for large graph sates of arbitrary (complex) topology.
We benchmark our scheme with two protocols where each connected component is
prepared in a node belonging to the component and subsequently distributed via
quantum repeaters to the remaining connected nodes. We show that the fidelity
of the generated graphs can be written as the partition function of a classical
Ising-type Hamiltonian. We give exact expressions of the fidelity of the linear
cluster and results for its decay rate in random graphs with arbitrary
(uncorrelated) degree distributions.Comment: 16 pages, 7 figure
Entanglement Percolation with Bipartite Mixed States
We develop a concept of entanglement percolation for long-distance singlet
generation in quantum networks with neighboring nodes connected by partially
entangled bipartite mixed states. We give a necessary and sufficient condition
on the class of mixed network states for the generation of singlets. States
beyond this class are insufficient for entanglement percolation. We find that
neighboring nodes are required to be connected by multiple partially entangled
states and devise a rich variety of distillation protocols for the conversion
of these states into singlets. These distillation protocols are suitable for a
variety of network geometries and have a sufficiently high success probability
even for significantly impure states. In addition to this, we discuss possible
further improvements achievable by using quantum strategies including
generalized forms of entanglement swapping.Comment: 6+ pages, 5 figures; Published versio