Electrically detected magnetic resonance using radio-frequency reflectometry.

The authors demonstrate readout of electrically detected magnetic resonance at radio frequencies by means of a LCR tank circuit. Applied to a silicon field-effect transistor at millikelvin temperatures, this method shows a 25-fold increased signal-to-noise ratio of the conduction band electron spin resonance and a higher operational bandwidth of >300 kHz compared to the kilohertz bandwidth of conventional readout techniques. This increase in temporal resolution provides a method for future direct observations of spin dynamics in the electrical device characteristics.

Radio-frequency reflectometry on large gated two-dimensional systems.

We have embedded an AlGaAs/GaAs based, gated two-dimensional (2D) hole system (2DHS) into an impedance transformer LC circuit and show that by using radio-frequency reflectometry it is possible to perform sensitive, large bandwidth, electrical resistance measurements of 2D systems at millikelvin temperatures. We construct a simple lumped element model where the gated 2DHS is described as a resistive transmission line. The model gives a qualitative understanding of the experimental results.

Bias spectroscopy and simultaneous single-electron transistor charge state detection of Si:P double dots.

We report a detailed study of low-temperature (mK) transport properties of a silicon double-dot system fabricated by phosphorous ion implantation. The device under study consists of two phosphorous nanoscale islands doped to above the metal-insulator transition, separated from each other and the source and drain reservoirs by nominally undoped (intrinsic) silicon tunnel barriers. Metallic control gates, together with an Al-AlO(x) single-electron transistor (SET), were positioned on the substrate surface, capacitively coupled to the buried dots.

Progress in silicon-based quantum computing.

We review progress at the Australian Centre for Quantum Computer Technology towards the fabrication and demonstration of spin qubits and charge qubits based on phosphorus donor atoms embedded in intrinsic silicon. Fabrication is being pursued via two complementary pathways: a 'top-down' approach for near-term production of few-qubit demonstration devices and a 'bottom-up' approach for large-scale qubit arrays with sub-nanometre precision. The 'top-down' approach employs a low-energy (keV) ion beam to implant the phosphorus atoms.