Coherent Phonon Manipulation in Coupled Mechanical Resonators

Hajime Okamoto, Imran Mahboob, Koji Onomitsu*, and Hiroshi Yamaguchi
Physical Science Laboratory, *Materials Science Laboratory

　Semiconductor nanomechanical resonators enable the pursuit of new physical phenomenon than can only be observed through the tiny mechanical displacement as well as enabling the development of nanoscience and nanotechnology. Coupling such nanomechanical resonators has recently emerged as a subject of interest, because the sympathetic oscillation dynamics in the coupled system expand the potential applications of nanomechanical objects such as highly precise sensors, signal amplifier, and logic gates. However, an obstacle to the further development of this architecture arises from the usually weak coupling between the nanomechanical components. This limits the ability to coherently transfer the vibration energy between the resonators within the ring-down time.
　We have realized the strong coupling and coherent energy transfer between two GaAs doubly-clamped beam resonators (Fig. 1(a)) by the parametric mode mixing technique [1, 2]. The piezoelectric modulation of the spring constant of one beam at the frequency difference between the two beams leads to the dynamic coupling of the two beams, enabling the cyclic (Rabi) oscillations of phonons between the two vibrational states (Fig. 1(b), (c)). The Rabi cycle period, i.e., the coupling strength, is adjustable by changing the gate voltage (Fig. 1(d)). As a result, the vibration energy can be quickly transferred from one beam to the other enabling the vibration of the original beam to be switched off on a time-scale orders of magnitude shorter than its ring-down time [3]. This quick energy transfer opens up the prospect of high-speed repetitive operations for sensors and logics using nanomechanical systems.
　This work was supported by KAKENHI.