Enhancing quantum synchronization through homodyne measurement, noise and squeezing

Quantum synchronization has been a central topic in quantum nonlinear dynamics. Despite rapid development in this field, very few have studied how to efficiently boost synchronization. Homodyne measurement emerges as one of the successful candidates for this task, but preferably in the semi-classical regime. In our work, we focus on the phase synchronization of a harmonic-driven quantum Stuart-Landau oscillator, and show that the enhancement induced by homodyne measurement persists into the quantum regime. Interestingly, optimal two-photon damping rates exist when the oscillator and driving are at resonance and with a small single-photon damping rate. We also report noise-induced enhancement in quantum synchronization when the single-photon damping rate is sufficiently large. Apart from these results, we discover that adding a squeezing Hamiltonian can further boost synchronization, especially in the semi-classical regime. Furthermore, the addition of squeezing causes the optimal two-photon pumping rates to shift and converge.