One Electron Makes Current Flow

Abstract

Even the smallest components in a modern desktop computer use tens of thousands of electrons at a time to implement classical logic (the conventional 1s and 0s of binary computation). A computer that operated on single electrons, however, could in principle implement quantum logic functions (quantum bits or “qubits” that could perform computational tasks that are beyond the ability of classical computers). One proposed architecture for a single-electron computer could be realized in a two-dimensional electron gas (2DEG), a special kind of reservoir in which electrons can travel without dissipation (1). On page 1169 of this issue, Fève et al. (2) report on an important step toward this vision: a device that can emit single electrons into a 2DEG and absorb them again on nanosecond time scales. With such a controllable electron source, researchers will now be able to set up one or more electrons in well-defined quantum states, which are crucial for any future quantum computer.