Entangling silicon spin qubits in a hybrid dot-donor system*

Quantum bits realized in hybrid systems harness the optimal features of multiple types of quantum systems. Silicon provides a particularly attractive platform for realizing hybrid semiconductor qubits, as it supports both nuclear and electron spin qubits in well-isolated atomic impurities as well as highly tunable quantum dot-based spin qubits. Recent experiments [1,2] combine the favorable properties of both systems to demonstrate full coherent control of a hybrid singlet-triplet qubit via exchange and an intrinsic magnetic gradient provided by the donor hyperfine interaction. In order to couple these qubits, we theoretically consider the capacitive interaction in the presence of hyperfine coupling and identify regimes of operation relevant for experiments. We also extend this analysis to investigate the electron spin-mediated interaction between the nuclear spins as a potential mechanism for entangling gates.

[1] P. Harvey-Collard et al., Nat. Commun. 8, 1029 (2017).
[2] M. Rudolph et al., 2016 IEEE International Electron Devices Meeting (IEDM), 34.1.1 (2016).