Controlled Operations in a Strongly Correlated Two-Electron Quantum Ring

We have analyzed the electronic spectrum and wave function characteristics of a strongly correlated two-electron quantum ring with model parameters close to those observed in experiments. The analysis is based on an exact diagonalization of the Hamiltonian in a large B-spline basis. We propose a new qubit pair for storing quantum information, where one component is stored in the total electron spin and one multivalued "quMbit" is represented by the total angular momentum. In this scheme the controlled NOT (CNOT) quantum gate is demonstrated with near 100% fidelity for a realistic far infrared electromagnetic pulse.