Bit Operation in a Parametrically Pumped Electromechanical Resonator


Imran Mahboob and Hiroshi Yamaguchi
Physical Science Laboratory

 More than 150 years ago Charles Babbage originated the idea of a programmable computer. Babbage conceived his analytical engine in a mechanical architecture where logic was performed by moving parts. In the microelectronics age these ground breaking ideas were forgotten as silicon transistor technology was the system of choice for implementing logic. We demonstrate that in the era of nanotechnology the mechanical computer can be revived and logic can be implemented by electromechanical systems.
 The Parametron is a logic processing system first developed 50 years ago [1]. It utilizes the parametrically excited resonance of a harmonic oscillator, where this oscillation has two stable phases separated by π radians, as the basis for logic operations. The computational architecture based on this principle was well developed using LC oscillators but was rendered obsolete by the transistor due to its high power consumption and integration difficulties in dense system architectures. To remedy these drawbacks, we propose to implement mechanical logic in the mould of the Parametron with electromechanical systems.
 In the first steps to this goal, we demonstrate both bit storage and bit flip operations in an electromechanical oscillator [2]. We do this by integrating a two dimensional electron system into the mechanical oscillator which enables electromechanical transduction via the piezoelectric effect [3]. This enables on-chip all electrical actuation of the parametric resonance and detection of the fundamental mode as well as switching between the two phases of oscillation i.e. all the necessary prerequisites for the electromechanical Parametron computer. The electromechanical bit operation demonstrated here paves the way for realizing a nanomechanical computer.

[1] E. Goto, Proc. IRE 47 (1959) 1304.
[2] I. Mahboob and H. Yamaguchi, Nature Nanotechnol. 3 (2008) 275.
[3] I. Mahboob and H. Yamaguchi, Appl. Phys. Lett. 92 (2008) 173109.

Fig. 1. A microscope image of the electromechanical resonator integrating a two dimensional electron system, multiple Schotkky contacted gold electrodes and a simplified circuit diagram which enabled the bit-flip operation to be implemented.
Fig. 2. (a): a schematic of the pulse sequence at frequency fs which enables bit storage and bit flip operations. (b) and (c): Experimental realization of the protocol described in (a) with fs=0.01 and 0.03 Hz.

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