Coherence, asymmetry, and quantum macroscopicity

Hyukjoon Kwon, Chae-Yeun Park, Kok Chuan Tan, Daekun Ahn, and Hyunseok Jeong
Phys. Rev. A 97, 012326 – Published 23 January 2018

Abstract

We investigate a measure of quantum coherence and its extension to quantify quantum macroscopicity. The coherence measure can also quantify the asymmetry of a quantum state with respect to a given group transformation. We then show that a weighted sum of asymmetry in each mode can be applied as a measure of macroscopic coherence. To exclude the effects of microscopic superpositions, we suggest a method to introduce a cutoff to the weighted sum that will specify the macroscopic portion of the coherence. This cutoff may be interpreted as the fuzziness for a given measurement outcome. Based on the suggested measures, we investigate the quantum macroscopicity for particular concrete examples in N-partite spin systems.

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  • Received 12 June 2017
  • Revised 17 October 2017

DOI:https://doi.org/10.1103/PhysRevA.97.012326

©2018 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & TechnologyGeneral Physics

Authors & Affiliations

Hyukjoon Kwon1, Chae-Yeun Park1,2, Kok Chuan Tan1, Daekun Ahn1, and Hyunseok Jeong1,*

  • 1Center for Macroscopic Quantum Control, Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Korea
  • 2Asia Pacific Center for Theoretical Physics, Pohang 37673, Korea

  • *h.jeong37@gmail.com

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Vol. 97, Iss. 1 — January 2018

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