High-Sensitivity Charge Detection with a Single-Lead Quantum Dot for Scalable Quantum Computation

A promising route toward large-scale quantum information processing is to use as qubits the spin states of individual phosphorus atoms in silicon. One challenge in making this system scalable, though, is to fit control and readout structures---which are necessarily bigger than the single-atom qubits---into a device at the same length scale. Combining rf measurement techniques with ultraprecise lithography, this study presents a charge sensor that can be fabricated at the atomic scale, needs only one electrical lead, and is capable of the sensitivity needed for single-shot dispersive readout of a lone electron's spin state.