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

### Submission summary

 As Contributors: Sayantan Choudhury Arxiv Link: https://arxiv.org/abs/2005.13555v1 (pdf) Date submitted: 2020-10-21 11:42 Submitted by: Choudhury, Sayantan Submitted to: SciPost Physics Academic field: Physics Specialties: Condensed Matter Physics - Theory Gravitation, Cosmology and Astroparticle Physics High-Energy Physics - Theory High-Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics Approaches: Theoretical, Phenomenological

### Abstract

In this paper, our prime objective is to apply the techniques of {\it parameter estimation theory} and the concept of {\it Quantum Metrology} in the form of {\it 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. {\it Quantum Metrology}, compared to {\it 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 {\it Quantum Metrology}, which beats the classical parameter estimation. We also present an interesting result of \textit{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.

###### Current status:
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