Identifying and avoiding singularity-induced local traps over control landscapes of spin chain systems

Qiuyang Sun, István Pelczer, Gregory Riviello, Re Bing Wu, Herschel Rabitz

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

The wide success of quantum optimal control in experiments and simulations is attributed to the properties of the control landscape, defined by the objective value as a functional of the controls. Prior analysis has shown that on satisfaction of some underlying assumptions, the landscapes are free of suboptimal traps that could halt the search for a global optimum with gradient-based algorithms. However, violation of one particular assumption can give rise to a so-called singular control, possibly bringing about local traps on the corresponding landscapes in some particular situations. This paper theoretically and experimentally demonstrates the existence of singular traps on the landscape in linear spin-1/2 chains with Ising couplings between nearest neighbors and with certain field components set to zero. The results in a two-spin example show how a trap influences the search trajectories passing by it, and how to avoid encountering such traps in practice by choosing sufficiently strong initial control fields. The findings are also discussed in the context of the generally observed success of quantum control.

Original languageEnglish (US)
Pages (from-to)29714-29722
Number of pages9
JournalPhysical Chemistry Chemical Physics
Volume17
Issue number44
DOIs
StatePublished - Jan 1 2015

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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