Beating the limits with initial correlations

Research output: Contribution to journalArticleScientificpeer-review


Research units

  • University of Kassel
  • University of Turku
  • Universite Bourgogne Franche-Comte
  • Technical University of Munich


Fast and reliable reset of a qubit is a key prerequisite for any quantum technology. For real world open quantum systems undergoing non-Markovian dynamics, reset implies not only purification, but in particular erasure of initial correlations between qubit and environment. Here, we derive optimal reset protocols using a combination of geometric and numerical control theory. For factorizing initial states, we find a lower limit for the entropy reduction of the qubit as well as a speed limit. The time-optimal solution is determined by the maximum coupling strength. Initial correlations, remarkably, allow for faster reset and smaller errors. Entanglement is not necessary.


Original languageEnglish
Article number113042
Pages (from-to)1-16
JournalNew Journal of Physics
Issue number11
Publication statusPublished - 1 Nov 2017
MoE publication typeA1 Journal article-refereed

    Research areas

  • quantum control, state preparation, superconducting qubits

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