Single-electron directional-coupler logic devices

Summary form only given. Recently, logic devices based on binary-decision-diagram (BDD) architecture were proposed. The building blocks are directional-coupler devices. We propose a new single-electron directional-coupler device using gated multiple-tunnel junctions. In one cycle of control voltage a fixed number of electrons, n, is transferred. The gate voltage modifies the Coulomb blockade regions of multiple tunnel junctions and controls the direction of information flow. A test chip was fabricated, consisting of one turnstile device and one single-electron directional coupler device. The experimental turnstile device shows the linear dependence of gate frequency and amplitude on direct current, I=nef; where e is the elementary charge. In the single-electron directional-coupler device, clear switching characteristics are obtained. For the construction of logic devices in BDD architecture, a multi-clocking scheme can be adopted to overcome the problem of series connection, as has been proposed in phase-locked single-electron logic.