Single molecules perform a variety of tasks in cells, from replicating, controlling and translating the genetic material to sensing the outside environment. These operations all require that specific actions take place. In a sense, each molecule must make tiny decisions. To make a decision, each “molecular machine ” must dissipate an energy Py in the presense of thermal noise Ny. The number of binary decisions that can be made by a machine which has dspace

This paper provides an overview of research developments toward nanometer-scale electronic switching devices for use in building ultra-densely integrated electronic computers. Specifically, two classes of alternatives to the field-effect transistor are considered: 1) quantum-effect and single-electron solid-state devices and 2) molecular electronic devices. A taxonomy of devices in each class is provided, operational principles are described and compared for the various types of devices, and the literature about each is surveyed. This information is presented in nonmathematical terms intended for a general, technically interested readership

Since optical communication is preferable for establishing connections exceeding a certain critical length, for large system sizes the beneficial use of normally conducting wires for the shortest connections becomes an edge effect and can be ignored. This suggests that the performance and cost of an all optical computer might not be much inferior to an optimal hybrid alternative. We argue that for applications for which high bit repetition rates are useful despite large propagation delays, it might make sense to contemplate the construction of an optical digital computer. 1.

of interconnection theory for optical digital computing