Irreversible logic operations inevitably discard information, setting fundamental limitations on the flexibility and the efficiency of modern computation. To circumvent the limit imposed by the von Neumann-Landauer (VNL) principle, an important objective is the development of reversible logic gates, as proposed by Fredkin, Toffoli, Wilczek, Feynman, and others. Here, we present a novel nanomechanical logic architecture for implementing a Fredkin gate, a universal logic gate from which any reversible computation can be built. In addition to verifying the truth table, we demonstrate operation of the device as an AND, OR, NOT, and FANOUT gate. Excluding losses due to resonator dissipation and transduction, which will require significant improvement in order to minimize the overall energy cost, our device requires an energy of order 10(4) kT per logic operation, similar in magnitude to state-of-the-art transistor-based technologies. Ultimately, reversible nanomechanical logic gates could play a crucial role in developing highly efficient reversible computers, with implications for efficient error correction and quantum computing.

We report signal amplification by 1/f(alpha) noise with stochastic resonance in a nonlinear nanomechanical resonator. The addition of 1/f(alpha) noise to a subthreshold modulation signal enhances the probability of an electrostatically driven resonator switching between its two vibrational states in the hysteretic region. Considering the prevalence of 1/f noise in the materials in integrated circuits, signal enhancement demonstrated here, using a fully on-chip electronic actuation/detection scheme, suggests beneficial use of the otherwise detrimental noise.

We present measurements of nonlinear coupling between various acoustic modes of a micromechanical resonator. Piezoelectric transduction allows measurement of both flexural and bulk longitudinal modes up to microwave frequencies, and we find that all modes of the device couple, regardless of type. This coupling thus provides a means of mechanical nonlinear signal processing across a wide range of frequencies. Through controlled simultaneous excitation, we quantify coupling strength by measuring the frequency shift in a detector mode in response to the known energy of a driven mode.

Stochastic resonance with white noise has been well established as a potential signal amplification mechanism in nanomechanical two-state systems. While white noise represents the archetypal stimulus for stochastic resonance, typical operating environments for nanomechanical devices often contain different classes of noise, particularly colored noise with a 1/f spectrum. As a result, improved understanding of the effects of noise color will be helpful in maximizing device performance. Here we report measurements of stochastic resonance in a silicon nanomechanical resonator using 1/f noise and Ornstein-Uhlenbeck noise types. Power spectral densities and residence time distributions provide insight into asymmetry of the bistable amplitude states, and the data sets suggest that 1/f α noise spectra with increasing noise color (i.e. α) may lead to increasing asymmetry in the system, reducing the achievable amplification. Furthermore, we explore the effects of correlation time τ on stochastic resonance with the use of exponentially correlated noise. We find monotonic suppression of the spectral amplification as the correlation time increases. PACS. 85.85.+j MEMS/NEMS -05.40.-a Fluctuation phenomena, noise, and Brownian motion -05.45.-a Nonlinear dynamics and chaos arXiv:0903.2522v1 [cond-mat.mes-hall]

We demonstrate the fabrication and operation of an integrated device containing a nanoelectromechanical system and an integrated detector. This on-chip silicon nanochannel field effect transistor is used to measure the motion of a silicon nanomechanical resonator at room temperature. Furthermore, we describe the operation of the device as a silicon-based room-temperature on-chip amplifier for improved displacement detection of nanomechanical resonators.