Possible realization of an ideal quantum computer in Josephson junction array

L. B. Ioffe, M. V. Feigel'man

Research output: Contribution to journalArticlepeer-review

87 Citations (Scopus)


We introduce a class of Josephson arrays which have nontrivial topology and exhibit a novel state at low temperatures. This state is characterized by long-range order in a two Cooper pair condensate and by a discrete topological order parameter. These arrays have degenerate ground states with this degeneracy "protected" from the external perturbations (and noise) by the topological order parameter. We show that in ideal conditions the low order effect of the external perturbations on this degeneracy is exactly zero and that deviations from ideality lead to only exponentially small effects of perturbations. We argue that this system provides a physical implementation of an ideal quantum computer with a built-in error correction and show that even a small array exhibits interesting physical properties such as superconductivity with double charge, 4e, and extremely long decoherence times.

Original languageEnglish
Article number224503
Pages (from-to)2245031-2245038
Number of pages8
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number22
Publication statusPublished - 1 Dec 2002
Externally publishedYes


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