Remote Actuation of an Electromechanical Resonator

　

Daiki Hatanaka, Imran Mahboob, and Hiroshi Yamaguchi
Physical Science Laboratory

　Electromechanical resonators with small mass and high quality-factor have attracted intensive attention due to their potential applications as sensors [1], signal processors [2] and to study macroscopic quantum phenomena [3]. Actuation of the electromechanical resonator is essential in order to access the various mechanical functions. In the actuation methods reported so far, mechanical oscillations were induced by directly applying a voltage to an electrode on the mechanical resonator. The presence of the electrode for these direct electrical actuations not only loads the resonator but can also yield Joule heating which increases the mechanical energy dissipation and thus degrades the resonator performance. In order to overcome these obstacles, a contact free driving technique that does not need the direct electrical actuation was developed [4].
　A GaAs/AlGaAs-based mechanical resonator containing a two dimensional electron gas (2DEG) and gold top-gates (TGs) was fabricated, which was placed inside a coil operating in the radio-frequency (RF) range as shown in Fig. 1. The mechanical resonator reveals the fundamental mode f_res = 172990.5 Hz at less than 200 mK as shown in the inset of Fig. 1. The coil shows a number of LC resonances (the upper panel in Fig. 2) and it emits RF waves to the mechanical resonator when the coil transmission is maximized. To demonstrate remote actuation using the RF waves, the mechanical response as function of the coil frequency f_coil ranging from 10 to 130 MHz was measured (the lower panel in Fig. 2). The RF wave’s amplitude was modulated at frequency f_AM and when f_AM = fres, the mechanical oscillator resonated at frequencies that corresponded to the LC resonances in the coil. The RF waves generated from the coil could drive the mechanical oscillator to resonance. This driving scheme enables the mechanical oscillations to be remotely induced and paves the way towards new applications for electromechanical resonators.

[1] A. N. Cleland and M. L. Roukes, Nature 392 (1998) 160.
[2] I. Mahboob and H. Yamaguchi, Nature Nanotech. 3 (2008) 275.
[3] A. D. O’Connell et al., Nature 464 (2010) 697.
[4] D. Hatanaka et al., Appl. Phys. Lett. 99 (2011) 103105.
　

Fig. 1. A schematic of the micron-sized mechanical resonator inside a coil and the experimental set-up. The inset shows piezoelectrically driven and detected mechanical response at an actuation voltage of 12 mVrms.		Fig. 2. The coil and the mechanical resonator response when excited by AM RF waves whilst sweeping the coil frequency with a power of -25 dBm.

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