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QMetrology from QCosmology: Study with Entangled Two Qubit Open Quantum System in De Sitter Space

by Sayantan Choudhury, Satyaki Chowdhury, Nitin Gupta, Abinash Swain

Submission summary

As Contributors: Sayantan Choudhury · Nitin Gupta
Arxiv Link: (pdf)
Date accepted: 2021-03-25
Date submitted: 2021-03-18 05:23
Submitted by: Choudhury, Sayantan
Submitted to: SciPost Physics Core
Academic field: Physics
  • Condensed Matter Physics - Theory
  • Gravitation, Cosmology and Astroparticle Physics
  • High-Energy Physics - Theory
  • High-Energy Physics - Phenomenology
  • Cosmology and Nongalactic Astrophysics
Approaches: Theoretical, Phenomenological


In this paper, our prime objective is to apply the techniques of parameter estimation theory and the concept of Quantum Metrology in the form of Fisher Information to investigate the role of certain physical quantities in the open quantum dynamics of a two entangled qubit system under the Markovian approximation. There exist various physical parameters which characterize such system, but can not be treated as any quantum mechanical observable. It becomes imperative to do a detailed parameter estimation analysis to determine the physically consistent parameter space of such quantities. We apply both Classical Fisher Information (CFI) and Quantum Fisher Information (QFI) to correctly estimate these parameters, which play significant role to describe the out-of-equilibrium and the long range quantum entanglement phenomena of open quantum system. Quantum Metrology, compared to classical parameter estimation theory, plays a two-fold superior role, improving the precision and accuracy of parameter estimation. Additionally, in this paper we present a new avenue in terms of Quantum Metrology, which beats the classical parameter estimation. We also present an interesting result of revival of out-of-equilibrium feature at the late time scales, arising due to the long range quantum entanglement at early time scale and provide a physical interpretation for the same in terms of Bell's Inequality Violation in early time scale giving rise to non-locality.

Published as SciPost Phys. Core 4, 006 (2021)

Author comments upon resubmission

Dear Editor,

Thank you very much for the previous correspondence and also we want to thank all the referees for giving us their valuable comments. We are thankful to one of the referees for accepting our previous version. Though there us objection by one new referee and another referee have asked few explanations. By following the details of both the reports we have sufficiently modified the revised version of the draft which we have uploaded in arXiv as well. In this regard, I would like to request the Editor-in-Charge to reconsider our paper for publication in SciPost.

Best regards,
Dr. Sayantan Choudhury (Corresponding Author)

List of changes

We have added the following changes:
1. We have provided all the explationations to the objection of one of the referees.
2. We have added discussion regarding to motivation and novelty of the work performed which was asked by another referee.
3. We have added new citations as suggested by one of the referees.

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