Quantum spatial search on graphs subject to dynamical noise

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

  • University of Milan
  • University of Turku

Abstract

We address quantum spatial search on graphs and its implementation by continuous-time quantum walks in the presence of dynamical noise. In particular, we focus on search on the complete graph and on the star graph of order N, also proving that noiseless spatial search shows optimal quantum speedup in the latter, in the computational limit N ≤ 1. The noise is modeled by independent sources of random telegraph noise (RTN), dynamically perturbing the links of the graph. We observe two different behaviors depending on the switching rate of RTN: fast noise only slightly degrades performance, whereas slow noise is more detrimental and, in general, lowers the success probability. In particular, we still find a quadratic speedup for the average running time of the algorithm, while for the star graph with external target node, we observe a transition to classical scaling. We also address how the effects of noise depend on the order of the graphs and discuss the role of the graph topology. Overall, our results suggest that realizations of quantum spatial search are possible with current technology and indicate the star graph as the perfect candidate for the implementation by noisy quantum walks, owing to its simple topology and nearly optimal performance for just a few nodes also.

Details

Original languageEnglish
Article number052347
Pages (from-to)1-8
JournalPhysical Review A
Volume98
Issue number5
Publication statusPublished - 27 Nov 2018
MoE publication typeA1 Journal article-refereed

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