Title: Investigation of Quantum Control of Donor Electrons in Silicon using Tight-binding Methods         

Speaker: Rajib Rahman, Purdue University        

Date/Time: Wednesday, April 2, 2008, 9:00 – 10:00 am

Location: CSRI Building/Room 90 (Sandia NM)

Brief Abstract: The P donor based quantum computer architecture in Si has received much attention in recent times due to its promise of scalability and coherence. As device sizes are getting smaller, devices with a few impurities are becoming increasingly common. Accurate operation of modern devices can be influenced by the quantum mechanical properties of a single or a few donors, and needs to be investigated in detail. Single donors also form the building blocks of a potentially scalable solid state quantum computer. We employed atomistic tight-binding theory to study quantum control of single/few impurities in Si. We investigated single donor physics relevant to quantum computing with respect to recent experiments, and established control parameters that can be tuned by the Stark effect. Discrepancies between theory and experiment that existed in literature regarding hyperfine, spin-orbit, and donor-interface orbital Stark effects are resolved by our calculations. We also study the gate control of the pseudo molecular states of a few coupled impurities, with the aim of demonstrating charge qubit control and coherent population transfer among donors. Finally, many-body electron interactions in spin qubits are investigated to highlight important controllability issues.

CSRI POC: Rick Muller, (505) 284-3669