Tae-Hee Lee and Robert M. Dickson of Georgia Institute of Technology in Atlanta have produced AND, OR, NOT and XOR logic gates using electroluminescent silver nanoparticles. Reported in the March 18 issue of PNAS, the optoelectronic devices promise to open the door for the development of molecular-scale electronics, including computers.Lee and Dickson exposed thin films of silver to a voltage-limited current for approximately 30 seconds, creating arrays of nanoscale break junctions and isolated silver nanoclusters. Varying the voltages of the two pulses that are used to stimulate optical emission in the nanoclusters enables the devices to perform basic addition operations and to act as logic gates.