US Patent 7117454 - Molecular AC Logic Gates

http://www.freepatentsonline.com/7117454.pdf

Hewlett-Packard is leading the way in molecular electronics by creating an enabling platform for the creation of complex molecular logic devices. This patent uses AC signals to enhance the detection of DC logic in a molecular logic system. Claim 1 reads:

1. A nanoscale logic gate comprising: an alternating-current source; two or more input signal lines connected through resistive elements to the alternating-current source and carrying direct-current logical states; a signal line connected to the alternating-current source and two or more input signal lines through a switch element that is either in a high-impedance state or a low-impedance state; and an output signal line that outputs an AC logical state.