A semiconductor structure in which the electron population is constrained in a two-dimensional quantum well, resulting in only one degree of freedom for the electrons. Such structures can be made using nanotechnology: molecular beam epitaxy can be used to produce quantum confinement in one dimension, and etching is used to create a stripe of semiconductor narrow enough to produce size quantization. Quantum wires display interesting electron-transport properties characteristic of highly quantized systems. See also quantum dot; nanoelectronics.