Integrating high-spin antimony donors with MOS quantum dots in silicon, Part 2: Flip-Flop qubit operation

Flip-flop qubits [1] are a new class of spin systems that encode quantum information in the combined electron–nuclear spin states of donor atoms in silicon. Unlike magnetically driven spins, flip-flop states allow all-electrical control through modulation of the hyperfine interaction, enabling faster and more scalable manipulation. Earlier experiments with phosphorus donors [2] showed coherent flip-flop control but with limited speed, due to the challenge in strongly modulating the hyperfine coupling. Here we demonstrate MHz-rate electrical driving of the flip-flop states of a high-spin antimony donor integrated with a MOS quantum dot. This setup enables the ideal flip-flop qubit operation, where the electron can be efficiently displaced between the donor and interface dot, resulting in strong hyperfine modulation. By tuning the gate voltages, we control the electron’s spatial wavefunction and hence the hyperfine coupling strength, observing an exponential increase in the Rabi frequency as the electron is pulled toward the dot. These measurements reveal the electrostatic tunability of the donor–dot hybrid system and provide a pathway toward fast, electrically driven operation of donor-based qudits in silicon quantum devices.



[1] G. Tosi et al, Nature Communications 8:450 (2017)

[2] R. Savytskyy et al., Science Advances 9, eadd9408 (2023)