Scalable solid-state quantum computer based on quantum dot pillar structures

We investigate an optically driven quantum computer based on electric dipol e transitions within coupled single-electron quantum dots. Our quantum regi ster consists of a free-standing n-type pillar containing a series of pairw ise coupled asymmetric quantum dots, each with a slightly different energy structure, and with grounding leads at the top and bottom of the pillar. As ymmetric quantum wells confine electrons along the pillar axis, and a negat ively biased gate wrapped around the center of the pillar allows for electr ostatic confinement in the radial direction. We self-consistently solve cou pled Schrodinger and Poisson equations and develop a design for a three-qub it quantum register. Our results indicate that a single gate electrode can be used to localize a single electron in each of the quantum dots. Adjacent dots are strongly coupled by electric dipole-dipole interactions arising f rom the dot asymmetry, thus enabling rapid computation rates. The dots are tailored to minimize dephasing due to spontaneous emission and phonon scatt ering and to maximize the number of computation cycles. The design is scala ble to a large number of qubits.