Vibrational resonance via a single-ion phonon laser

Vibrational resonances are ubiquitous in various nonlinear systems and play crucial roles in detecting weak low-frequency signals and developing highly sensitive sensors. Here we demonstrate vibrational resonance, for the first time, utilizing a single-ion phonon laser system exhibiting Van der Pol-type nonlinearity. To enhance the response of the phonon laser system to weak signals, we experimentally realize continuously tunable symmetry of the bistability in the phonon laser system via optical modulation, and achieve the maximum vibrational resonance amplification of 23 dB. In particular, our single-ion phonon laser system relaxes the frequency separation condition and exhibits the potential of multi- frequency signal amplification using the vibrational resonance. Our study employs the phonon laser to study and optimize the vibrational resonance with simple and well-controllable optical technology, which holds potential applications in developing precision metrology and single-ion sensors with on-chip ion traps.