Squeezing properties and parameter estimation in a driven Swanson oscillator damped in a thermal reservoir
Phys. Rev. A 114, 013706 – Published 6 July, 2026
DOI: https://doi.org/10.1103/wvy8-wjkw
Abstract
The quadrature squeezing and quantum Fisher information in a driven non-Hermitian Swanson oscillator coupled to a thermal bath are studied. Analytically solving the master equation, we find that the system reaches a Gaussian steady state in the -symmetric regime. Quadrature squeezing as a resource for parameter estimations of temperature and frequency is extensively investigated. Due to the asymmetric two-photon annihilation and creation processes, the positivity of quadrature variances provides a stricter constraint depending on the temperature compared with its Hermitian counterpart. This leads to the absence of exceptional points. However, in certain parameter regimes, quadrature squeezing remains robust and exceeds its Hermitian counterpart, while the variances are more sensitive to temperature and frequency. These advantages lead to the enhancement of temperature and frequency estimation. Importantly, when the Swanson oscillator is coherently driven off resonantly, the non-Hermiticity results in the encoding of temperature information in one of the first-order moments. This distinctive difference from its Hermitian counterpart provides a different way to design a quantum thermometer. Our work establishes the non-Hermitian Swanson oscillator as a viable platform for high-precision Gaussian quantum metrology.
