Study Demonstrates Ultra-High Q-Factors Behave Nonlinearly
11 December 2013
Scientists at the Institute of Photonic Sciences (ICFO) have measured the highest-ever quality factor (Q-factor) seen in nano- or micromechanical systems by optically levitating nanoparticles in a high vacuum environment, demonstrating for the first time that ultra-high Q-factor nano-resonators basically behave nonlinearly.
The work of the ICFO team made it possible to observe the highest force sensitivity ever achieved with a nano-mechanical resonator at room temperature through a combination of an ultra-high Q-factor and the tiny mass of the nanoparticles. In fact, the system is so sensitive that the weak forces occurring as a result of collisions between the particles and the residual air molecules were strong enough to drive it into the nonlinear regime. The levitating nanoparticle could be also used as a force sensor when combined with feedback cooling given its sensitivity to extremely weak interactions like non-Newtonian gravity-like forces and forces arising from quantum vacuum fluctuations.
While thermal motion is a phenomenon already detected in nano-mechanical systems, observing its nonlinear features is a "true novelty," bringing knowledge of how these high-Q nano-mechanical systems behave to a new level, said Jan Gieseler, researcher at ICFO Institute of Photonics Sciences. He hopes that this new class of nano-mechanical oscillators will give a boost to ultra-sensitive force testing and contribute to experimental investigation of quantum physics.
The study, published in the journal Nature Physics, was supported by researchers at the Plasmon Nano-optics group and the Nano-Photonics group from the Photonics Laboratory (ETH Zurich) and the Fundació Cellex Barcelona through its Nest program.