Deep-sub-voltage nanoelectronics are integrated circuits (ICs) operating near theoretical limits of energy consumption per unit of processing. These devices are intended to address the needs of applications such as wireless sensor networks which have dramatically different requirements from traditional electronics. For example, for microprocessors where performance is primary metric of interest, but for some new devices, energy per instruction may be a more sensible metric.

The tiny autonomous devices (smartdust

Smartdust

Smartdust is a hypothetical system of many tiny microelectromechanical systems such as sensors, robots, or other devices, that can detect, for example, light, temperature, vibration, magnetism or chemicals; are usually networked wirelessly; and are distributed over some area to perform tasks,...

 or autonomous Microelectromechanical systems

Microelectromechanical systems

Microelectromechanical systems is the technology of very small mechanical devices driven by electricity; it merges at the nano-scale into nanoelectromechanical systems and nanotechnology...

 as examples) on the basis of deep-sub-voltage nanoelectronics will require much increase of capacity density as in capacitors the energy depends quadratically from voltage http://www.nanometer.ru/2007/10/17/nanoionnie_superkondensatori_4879/PROP_FILE_files_2/Despotuli_Andreeva__Modern_Electronics_2007_rus_eng_translation_4.pdf.

The important case of fundamental ultimate limit for logic operation is the reversible computing

Reversible computing

Reversible computing is a model of computing where the computational process to some extent is reversible, i.e., time-invertible. A necessary condition for reversibility of a computational model is that the transition function mapping states to their successors at a given later time should be...

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