Parametric and feedback-controlled multiparameter quantum estimation in a double cavity optomechanics: steady and dynamical state

Multiparameter quantum estimation in open optomechanical systems is fundamentally constrained by dissipation, thermal fluctuations, and measurement incompatibility. In this work, we investigate a coupled-cavity optomechanical platform in which two mechanical modes interact with driven optical cavities, two-mode squeezed vacuum, intracavity degenerate parametric amplification, and coherent optical feedback. Using the continuous-variable Gaussian-state formalism, we derive the linearized quantum Langevin dynamics and steady-state covariance matrix and evaluate the quantum Fisher information matrices associated with simultaneous estimation of the optomechanical coupling strength and cavity dissipation rate. We characterize the precision bounds using the symmetric and right logarithmic derivative formalisms and employ $\mathcal{B}_{\rm MI}=\max\{\mathcal{B}_S,\mathcal{B}_R\}$ as a comparative figure of merit within the SLD/RLD framework. We find that parametric amplification can substantially reduce , demonstrating an enhancement of multiparameter sensitivity over a broad range of operating conditions. In contrast, coherent feedback produces a nonmonotonic modification of the estimation precision, with its effect depending sensitively on the feedback reflectivity, phase, squeezing strength, and thermal occupation. This behavior reveals that coherent feedback acts not simply as an enhancing or degrading mechanism, but as a tunable resource for engineering the quantum fluctuations and parameter-dependent correlations of the optomechanical state. We further analyze the transient and steady-state regimes and identify parameter regions in which squeezing and parametric amplification provide the largest metrological gain.

Source: arXiv:2609.05402v1 - http://arxiv.org/abs/2609.05402v1 PDF: https://arxiv.org/pdf/2609.05402v1 Original Link: http://arxiv.org/abs/2609.05402v1