Quantum paradox of choice: More freedom makes summoning a quantum state harder

Emily Adlam and Adrian Kent
Phys. Rev. A 93, 062327 – Published 21 June 2016

Abstract

The properties of quantum information in space-time can be investigated by studying operational tasks, such as “summoning,” in which an unknown quantum state is supplied at one point and a call is made at another for it to be returned at a third. Hayden and May [arXiv:1210.0913] recently proved necessary and sufficient conditions for guaranteeing successful return of a summoned state for finite sets of call and return points when there is a guarantee of at most one summons. We prove necessary and sufficient conditions when there may be several possible summonses and complying with any one constitutes success, and we demonstrate the existence of an apparent paradox: The extra freedom makes it strictly harder to complete the summoning task. This result has practical applications for distributed quantum computing and cryptography and implications for our understanding of relativistic quantum information and its localization in space-time.

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  • Received 15 August 2015
  • Revised 14 September 2015

DOI:https://doi.org/10.1103/PhysRevA.93.062327

©2016 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & Technology

Authors & Affiliations

Emily Adlam1 and Adrian Kent1,2

  • 1Centre for Quantum Information and Foundations, DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
  • 2Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario, Canada N2L 2Y5

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Issue

Vol. 93, Iss. 6 — June 2016

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