Scalable Quantum Computing With “Enhancement” Quantum Dots

We propose a novel scheme of solid state realization of a quantum computer based on single spin “enhancement mode” quantum dots (QD) as building blocks. In the enhancement mode QD, just one electron can be brought into initially empty quantum dot, in contrast to the depletion mode QD based on expelling of electrons from multi-electron QDs by gates. The quantum computer architectures based on depletion mode QDs is confronted by several challenges, making scalability of that approach difficult. These challenges can be successfully overcome by the approach based on enhancement mode capable of producing a lateral square array of quantum dots with versatile functionalities. These functionalities allow transportation of qubits, including teleportation and error correction based on straightforward one and two-qubit operations. We describe the physical properties and demonstrate experimental characteristics of the enhancement QD based on single-electron transistors (SETs) using InAs/GaSb composite quantum wells. We discuss the material aspects of the QD quantum computing, including advantages of materials with large spin splittings such as InAs and perspectives of enhancement mode approach in materials such as Si. PACS: 73.21.La, 03.67-a, 81.07.Ta, 03.67.Lx