Global symmetry is unnecessary for fast quantum search

Jonatan Janmark, David A. Meyer, Thomas G. Wong

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


Grover's quantum search algorithm can be formulated as a quantum particle randomly walking on the (highly symmetric) complete graph, with one vertex marked by a nonzero potential. From an initial equal superposition, the state evolves in a two-dimensional subspace. Strongly regular graphs have a local symmetry that ensures that the state evolves in a three-dimensional subspace but most have no global symmetry. Using degenerate perturbation theory, we show that quantum random walk search on known families of strongly regular graphs, nevertheless, achieves the full quantum speed-up of Θ(N), disproving the intuition that fast quantum search requires global symmetry.

Original languageEnglish (US)
Article number210502
JournalPhysical Review Letters
Issue number21
StatePublished - May 28 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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