Electronic control and readout of qubits based on single impurity states in semiconductors

The authors demonstrate that a semiconductor n+∕i∕n+ junction is the most suitable candidate for electronic control and readout of semiconductor qubits based on shallow impurities. Tuning of the doping levels in n+ regions and self-induced interface barriers ensure that an impurity atom placed in i region is populated with one electron in equilibrium. They analyze Li donors in Si and show that a large signal qubit readout can be realized via polarization selective photoexcitation of resonant cotunneling current through an excited impurity state.