Towards the quantum internet of the mid-21st C: building quantum bits in silicon

Professor David Jamieson

The 2012 Physics Nobel prize recognises Serge Haroche and David Wineland for their pioneering work in measuring and manipulating individual quantum systems with many consequences including the first steps towards a quantum computer.  Their work involved the manipulation of photons in cavities and the laser cooling of trapped ions in a vacuum.  This presentation describes a different approach to quantum computer technology based on engineered single donor atoms in the most important material of the IT industry: silicon.  Ultimately this approach aims to exploit the fact that isotopically pure 28-Si is free of unpaired spins: a “semiconductor vacuum”.  Our approach is to engineer silicon nano-scale Complementary Metal-Oxide-Semiconductor (CMOS) field effect devices with a single phosphorous atom implanted with a deterministic doping method that is cited by the International semiconductor roadmap for 2011.  Our devices have now proved the ability to perform single shot readout of the donor electron spin.  We use electron spin resonance to drive Rabi oscillations to show a coherence time (T2) exceeding 200 µs suggesting a single electron spin can be used as a long-lived quantum bit.  Further, the same device has allowed us to perform nuclear magnetic resonance on the single 31-P nuclear spin by coupling the electron and nuclear spins and hence providing access to an even longer-lived nuclear qubit.  This presentation reviews the remaining challenges of building a large scale silicon quantum device for computation and communication that will continue to sustain our civilization built on the band-gap of silicon throughout the 21st C.