A Noise-Assisted Reprogrammable Nanomechanical Logic Gate

Abstract

We present a nanomechanical device, operating as a reprogrammable logic gate, and performing fundamental logic functions such as AND/OR and NAND/NOR. The logic function can be programmed (e.g., from AND to OR) dynamically, by adjusting the resonator's operating parameters. The device can access one of two stable steady states, according to a specific logic function; this operation is mediated by the noise floor which can be directly adjusted, or dynamically "tuned" via an adjustment of the underlying nonlinearity of the resonator, i.e., it is not necessary to have direct control over the noise floor. The demonstration of this reprogrammable nanomechanical logic gate affords a path to the practical realization of a new generation of mechanical computers.A practical realization of a nanomechanical logic device, capable of performing fundamental logic operations, is yet to be demonstrated despite a longstanding effort toward scalable mechanical computation. [1][2][3][4] This effort can be traced back to 1822 (at least), when Charles Babbage presented a mechanical computing device that he called the "Difference Engine", to the Royal Astronomical Society. 1 Before this event, though, the search for mechanical computing devices had already been inherent in attempts to build machines capable of computation. This search has, today, taken on added urgency as we seek to exploit emerging techniques for the manipulation of matter at nanometer length scales. With Boole's ideas on logic operations with two states an added dimension to computing, logic elements or gates have come to dominate modern computation. However mechanical logic, especially at the very small length scales and in the presence of a noise floor, has proven difficult to realize despite some recent experimental efforts. [5][6][7] The control and manipulation of mechanical response at nanometer scales can be realized by exploiting a (seemingly) counterintuitive physical phenomenon, stochastic resonance (SR): 8 in a noisy nonlinear mechanical system, the controlled addition of noise can enhance the system response to an external stimulus. Signal amplification in such a setup has been experimentally realized in nonlinear nanomechanical resonators configured as two-state devices. [9][10][11] Recently, it has been demonstrated 12 that when two square waves are applied as input stimuli to a two-state system, the response can result in a specific logical output with a probability (for obtaining this output) controlled by the noise intensity. Furthermore, changing the threshold (either via adjusting the nonlinearity strength or applying a controlled asymmetrizing dc signal) can change or "morph" the system output into a different logic operation. 12 Our experimental logic device consists of a nanomechanical resonator, operating in the nonlinear regime, wherein two different vibrational states coexist; for an underdamped system underpinned by an a priori monostable (but nonparabolic) potential energy function, these vibrational steady states are induced by biasing the...

Neuron dynamics in the presence of1/fnoise

“…Noise provides a critical barrier for the development of sensitive electronic and mechanical devices, particularly at the nanoscale [2,3]. Increasingly, researchers are focusing on exploring innovative, non-traditional device design and control strategies that exploit the ambient noise [4][5][6][7][8][9][10][11]. In this regard, there are clear advantages to understanding how nature has managed to harness noise in a setting whose primary (apparent) function is to manage information.…”

Towards electromechanical computation: An alternative approach to realize complex logic circuits

“…Second is the fact that the signal waveforms as logic inputs and logic outputs are often of different forms. [10][11][12][13][14][15][16] Apart from the work in Ref. 14, these unavoidable obstacles have restricted the development of complex logic circuits based on resonators.…”

“…8 The other stream of research has focused on the development of logic devices based on both linear and nonlinear operations of the MEMS/NEMS resonators. [10][11][12][13][14][15][16] The first resonator-based logic gates were realized by utilizing the presence of high (low) amplitude of vibration at on-resonance (offresonance) of a NEMS resonator in the linear regime. 10 Later, the bistability of a nonlinear NEMS resonator was used to realize a reprogrammable logic function, such as 2-bit AND/ NAND and OR/NOR gates.…”

“…10 Later, the bistability of a nonlinear NEMS resonator was used to realize a reprogrammable logic function, such as 2-bit AND/ NAND and OR/NOR gates. 11 A universal logic device capable of performing parallel operations of 2-bit AND, OR, and XOR logic functions as well as multi-bit logic operations was realized based on a parametrically excited electromechanical resonator. 12,13 Later, several components of a microcomputer, namely, a byte memory, a shift register, and a controlled-Not gate, have been successfully realized based on the parametric electromechanical excitation.…”

Achieving high bit rate logical stochastic resonance in a bistable system by adjusting parameters

“…LSR has been found to occur in a wide variety of nonlinear systems including electrical systems, [5][6][7] optical systems [8,9] mechanical, [10] chemical [11] and biological systems. [12,13] Theoretical studies have been carried out for investigating the effects of different classes of noises like non-Gaussian noise [14] , colored noise [15] , and 1/f noise [16] on LSR in nonlinear systems.…”