High-Fidelity Rapid Initialization and Read-Out of an Electron Spin via the Single DonorD−Charge State

We demonstrate high-fidelity electron spin read-out of a precision placed single donor in silicon via spin selective tunneling to either the $D^{+}$ or $D^{-}$ charge state of the donor. By performing read-out at the stable two electron $D^0\leftrightarrow D^{-}$ charge transition we can increase the tunnel rates to a nearby single electron transistor charge sensor by nearly 2 orders of magnitude, allowing faster qubit read-out (1 ms) with minimum loss in read-out fidelity (98.4%) compared to read-out at the $D^{+}\leftrightarrow D^0$ transition (99.6%). Furthermore, we show that read-out via the $D^{-}$ charge state can be used to rapidly initialize the electron spin qubit in its ground state with a fidelity of $F_I=99.8\%$.