License: Creative Commons Attribution 4.0 International license (CC BY 4.0)
When quoting this document, please refer to the following
DOI: 10.4230/LIPIcs.TQC.2021.10
URN: urn:nbn:de:0030-drops-140054
URL: http://dagstuhl.sunsite.rwth-aachen.de/volltexte/2021/14005/
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Le Gall, François ; Nishimura, Harumichi ; Yakaryılmaz, Abuzer

Quantum Logarithmic Space and Post-Selection

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LIPIcs-TQC-2021-10.pdf (0.7 MB)

Abstract

Post-selection, the power of discarding all runs of a computation in which an undesirable event occurs, is an influential concept introduced to the field of quantum complexity theory by Aaronson (Proceedings of the Royal Society A, 2005). In the present paper, we initiate the study of post-selection for space-bounded quantum complexity classes. Our main result shows the identity PostBQL = PL, i.e., the class of problems that can be solved by a bounded-error (polynomial-time) logarithmic-space quantum algorithm with post-selection (PostBQL) is equal to the class of problems that can be solved by unbounded-error logarithmic-space classical algorithms (PL). This result gives a space-bounded version of the well-known result PostBQP = PP proved by Aaronson for polynomial-time quantum computation. As a by-product, we also show that PL coincides with the class of problems that can be solved by bounded-error logarithmic-space quantum algorithms that have no time bound.

BibTeX - Entry

@InProceedings{legall_et_al:LIPIcs.TQC.2021.10,
  author =	{Le Gall, Fran\c{c}ois and Nishimura, Harumichi and Yakary{\i}lmaz, Abuzer},
  title =	{{Quantum Logarithmic Space and Post-Selection}},
  booktitle =	{16th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2021)},
  pages =	{10:1--10:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-198-6},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{197},
  editor =	{Hsieh, Min-Hsiu},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/opus/volltexte/2021/14005},
  URN =		{urn:nbn:de:0030-drops-140054},
  doi =		{10.4230/LIPIcs.TQC.2021.10},
  annote =	{Keywords: computational complexity, space-bounded quantum computation, post-selection}
}

Keywords: computational complexity, space-bounded quantum computation, post-selection
Collection: 16th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2021)
Issue Date: 2021
Date of publication: 22.06.2021

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