Linewidth narrowing and enhanced sensing in non-Hermitian circuit systems via anti-PT symmetry

Precision detection and weak signal amplification are vital for applications in quantum sensing, optics, acoustics, and electronics, where narrow linewidths and high sensitivity are crucial. Traditional methods, relying on high-quality factor resonators or hybrid systems with external feedback, often struggle with complexity, environmental sensitivity, and integration challenges. Advances in non-Hermitian physics and parity-time (PT) symmetry, particularly exceptional points (EPs), offer unique opportunities by leveraging coalescing eigenstates for frequency splitting sensing. However, PT systems require precise gain-loss balance and multi-resonance-mode setups, while EP-based sensors amplify both signals and noise, limiting their robustness. To tackle these challenges, we propose a single-resonator system with intrinsic anti-PT symmetry, incorporating a dual-channel excitation mechanism that enables dynamic adjustment of loss and coupling for precise resonance control. This design achieves an 80% linewidth reduction and dramatically enhances peak signal and sensitivity by 24.4-fold and 125-fold, respectively, offering a compact, high-performance solution for the next-generation sensing applications.