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Comment to Spatial Search by Quantum Walk is Optimal for Almost all Graphs

Quantum Physics 2020-09-29 v1

Abstract

This comment is to correct the proof of optimality of quantum spatial search for Erd\H{o}s-R\'enyi graphs presented in `Spatial Search by Quantum Walk is Optimal for Almost all Graphs' (https://doi.org/10.1103/PhysRevLett.116.100501). The authors claim that if plog3/2(n)np\geq \frac{\log^{3/2}(n)}{n}, then the CTQW-based search is optimal for almost all graphs. Below we point the issues found in the main paper, and propose corrections, which in fact improve the result to p=ω(log(n)/n)p=\omega(\log(n)/n) in case of transition rate γ=1/λ1\gamma = 1/\lambda_1. In the case of the proof for simplified transition rate 1/(np)1/(np) we pointed a possible issue with applying perturbation theory.

Keywords

Cite

@article{arxiv.2009.13309,
  title  = {Comment to Spatial Search by Quantum Walk is Optimal for Almost all Graphs},
  author = {Ryszard Kukulski and Adam Glos},
  journal= {arXiv preprint arXiv:2009.13309},
  year   = {2020}
}

Comments

The comments applies for the paper found in https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.100501

R2 v1 2026-06-23T18:50:48.734Z