31,348 research outputs found
Single-Step Distillation Protocol with Generalized Beam Splitters
We develop a distillation protocol for multilevel qubits (qudits) using
generalized beam splitters like in the proposal of Pan et al. for ordinary
qubits. We find an acceleration with respect to the scheme of Bennet et al.
when extended to qudits. It is also possible to distill entangled pairs of
photons carrying orbital angular momenta (OAM) states that conserves the total
angular momenta as those produced in recent experiments.Comment: REVTEX4 file, color figure
Distillation Protocols for Mixed States of Multilevel Qubits and the Quantum Renormalization Group
We study several properties of distillation protocols to purify multilevel
qubit states (qudits) when applied to a certain family of initial mixed
bipartite states. We find that it is possible to use qudits states to increase
the stability region obtained with the flow equations to distill qubits. In
particular, for qutrits we get the phase diagram of the distillation process
with a rich structure of fixed points. We investigate the large- limit of
qudits protocols and find an analytical solution in the continuum limit. The
general solution of the distillation recursion relations is presented in an
appendix. We stress the notion of weight amplification for distillation
protocols as opposed to the quantum amplitude amplification that appears in the
Grover algorithm. Likewise, we investigate the relations between quantum
distillation and quantum renormalization processes.Comment: REVTEX4 file, 12 pages, 3 tables, color figure
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