Silicon-based quantum computing using buried donor architectures

Full text: Quantum computers have the potential to unveil a new paradigm of information processing via the coherent control of quantum bits (qubits). Solid-state implementations based on superconductors and semiconductors are particularly promising due to the prospect of producing large numbers of qubits via integrated circuit fabrication technology. Of these, the Kane Si:P scheme has generated great interest because of the long coherence times of spins in silicon. This and related Si schemes (such as the Si:P charge qubit) require the positioning of single phosphorus atoms in silicon, registered to surface control gates with high precision, together with an ability to read out a single spin or charge, important strides in construction of atomically-precise P atom arrays in Si have been demonstrated over the past few years using a bottom-up assembly approach, while controlled single ion implantation has recently been used to construct Si:P qubit test devices with a precise number of P atoms using more conventional top-down nanotechnologies. This presentation will discuss the challenges of fabricating, controlling and measuring such single donor qubits, in particular those constructed via single ion implantation. Experimental results showing the gate-controlled transfer of single electrons between two buried Si:P quantum dots, each containing - 600 phosphorus atoms, with non-invasive detection using rf single electron transistors (SETs) will be presented, together with recent data on devices with only a few (less than ten) phosphorus donors. Copyright (2005) Australian Institute of Physics