Quantum information processing using designed defect states in: 2D anti-dot lattices

We propose a new physical implementation of spin qubits for quantum information processing, namely defect states in antidot lattices de¯ned in the two-dimensional electron gas at a semiconductor heterostructure. Calculations of the band structure of the periodic antidot lattice are presented. A point defect is created by removing a single antidot, and calculations show that localized states form that are to a high degree localized within the defect, with an energy structure which is robust against thermal dephasing. The exchange coupling between two electrons con¯ned to two tunnel-coupled defect states is calculated numerically.We ¯nd results reminiscent of double quantum dot structures, indicating that the suggested structure is a feasible physical implementation of spin qubits.