Strong negative nonlinear friction from induced two-phonon processes in vibrational systems

Area of Science:

• Physics
• Nonlinear Dynamics
• Electromechanical Systems

Background:

• Self-sustained vibrations are common in various systems and often linked to negative linear friction.
• Positive nonlinear friction typically prevents runaway vibration amplitudes.
• Controlling these vibrations is crucial for applications in lasers, clocks, and biological systems.

Purpose of the Study:

• To investigate the effects of negative nonlinear friction on oscillator dynamics.
• To demonstrate that negative nonlinear friction can overcome positive linear friction.
• To explore the conditions for self-sustained vibrations and forced responses.

Main Methods:

• Utilizing a modulated electromechanical resonator.
• Applying a drive to excite specific phonon modes (two of the studied mode, one of a faster decaying high-frequency mode).
• Analyzing the generic features of oscillator dynamics under these conditions.

Main Results:

• Negative nonlinear friction was successfully implemented and shown to be strong enough to dominate positive linear friction at large amplitudes.
• Self-sustained vibrations were observed to require an initial activation.
• A distinct branch of large-amplitude forced vibrations emerged when a resonant force was applied, separate from the small-amplitude response.

Conclusions:

• Negative nonlinear friction can be engineered in electromechanical resonators.
• Oscillator behavior, including the requirement for activation of self-sustained vibrations, is significantly altered by negative nonlinear friction.
• The emergence of isolated large-amplitude forced vibration branches offers new possibilities for controlling oscillatory phenomena.