Quantum Complexity of Testing Group Commutativity

  • Authors:
  • Frederic Magniez;Ashwin Nayak

  • Affiliations:
  • CNRS, LRI - batiment 490, Universite Paris-Sud, 91405 Orsay cedex, France;Department of Combinatorics and Optimization and Institute for Quantum Computing, University of Waterloo, 200 University Ave. W., Waterloo, Ontario N2L 3G1, Canada

  • Venue:
  • Algorithmica
  • Year:
  • 2007

Quantified Score

Hi-index 0.00

Visualization

Abstract

We consider the problem of testing the commutativity of a black-box group specified by its k generators. The complexity (in terms of k) of this problem was first considered by Pak, who gave a randomized algorithm involving O(k) group operations. We construct a quite optimal quantum algorithm for this problem whose complexity is in $\tilde{O}(k^{2/3})$. The algorithm uses and highlights the power of the quantization method of Szegedy. For the lower bound of $\Omega(k^{2/3})$, we give a reduction from a special case of Element Distinctness to our problem. Along the way, we prove the optimality of the algorithm of Pak for the randomized model.