 Quantum point contact

A short electrostatically defined constriction connecting two electron reservoirs. Transverse confinement produces transport modes, and sufficiently narrow contacts can collimate carriers for electron-focusing experiments. Its quantum conductance depends on mode transmission; an opening described only as narrower than a micrometre is not automatically in a single-mode limit.

A Quantum Point Contact (QPC) is a nanoscale structure that allows the study of quantum transport phenomena in one-dimensional conductors. It is typically formed in a two-dimensional electron gas (2DEG) system, often created in semiconductor heterostructures. The QPC can be thought of as a narrow constriction through which electrons can tunnel, and its width can be controlled with high precision. **Key Features of Quantum Point Contacts:** 1.