Year: 2026
Type: article
Abstract: We study the metrological properties of a continuously monitored Kitaev chain in the presence of imperfect detection. The system is conditioned on a no-click record, while each emitted fermion is registered only with probability $0\leq q\leq 1$. Because the conditional dynamics remains Gaussian, the steady state is fully characterized by the fermionic correlation matrix. This allows a direct evaluation of the quantum Fisher information and of the mean Uhlmann curvature. For perfect detection, the monitored steady state retains a singular critical structure and the quantum Fisher information with respect to the chemical potential becomes super-extensive. For any $q<1$, imperfect detection introduces a finite smoothing length that rounds the singularity and restores extensive scaling. Treating the detector efficiency as an additional estimation parameter reveals a generic multiparameter incompatibility for imperfect detection, with compatibility recovered only in the perfect-detection limit, where the mean Uhlmann curvature vanishes. These results show that incomplete trajectory information destroys the metrological enhancement associated with monitored criticality through a mechanism distinct from ordinary thermal smearing.
Source: Quantum Science and Technology
Language: English
Topic: Quantum many-body systems
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,895
Funders: European Commission, NextGenerationEU
OpenAlex ID: W7171507549