Direct quantum process tomography via measuring sequential weak values of incompatible observables

Yosep Kim, Yong Su Kim, Sang Yun Lee, Sang Wook Han, Sung Moon, Yoon Ho Kim, Young Wook Cho

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52 Citations (Scopus)


The weak value concept has enabled fundamental studies of quantum measurement and, recently, found potential applications in quantum and classical metrology. However, most weak value experiments reported to date do not require quantum mechanical descriptions, as they only exploit the classical wave nature of the physical systems. In this work, we demonstrate measurement of the sequential weak value of two incompatible observables by making use of two-photon quantum interference so that the results can only be explained quantum physically. We then demonstrate that the sequential weak value measurement can be used to perform direct quantum process tomography of a qubit channel. Our work not only demonstrates the quantum nature of weak values but also presents potential new applications of weak values in analyzing quantum channels and operations.

Original languageEnglish
Article number192
JournalNature communications
Issue number1
Publication statusPublished - 2018 Dec 1

Bibliographical note

Funding Information:
This work was supported by the KIST institutional programs (Project Nos 2E27231, 2E26780, and 2E27230-17-P005), by the National Research Foundation of Korea (Grant Nos 2016R1A2A1A05005202 and 2016R1A4A1008978) and by ICT R&D program of MSIP/IITP (Grant No. B0101-16-1355). Y.K. acknowledges support from the Global Ph. D. Fellowship by the National Research Foundation of Korea (Grant No. 2015H1A2A1033028).

Publisher Copyright:
© 2018 The Author(s).

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)


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