1. A crossbar that implements an AND logic gate, the crossbar comprising: a nanowire crossbar with two or more layers of approximately parallel nanowires; a number of configurable, tunneling resistor junctions that each interconnects a nanowire in a first layer of approximately parallel nanowires with a nanowire in a second layer of approximately parallel nanowires, wherein the tunneling resistors have current-to-voltage inversion symmetry; two nanowires in the first layer that each receive an electrical signal that represents an input logical value; a nanowire in the first layer that receives a pull-up voltage; and a nanowire in the second layer interconnected to the nanowires in the first layer, the nanowire in the second layer carries an electrical signal representing an AND logic gate output logic value.