Direct entanglement protocol for three cavity-coupled spin qubits

Spin qubits based on gate-defined quantum dots have been developing over the past two decades into a leading contender for practical quantum hardware[1]. This is in part due to the prospect of long-range spin-spin interaction. The ability to operate within an all-to-all coupling geometry holds benefit[2], and it has only recently been demonstrated that remote spin-based qubits in double quantum dot architectures can interact via exchange of virtual cavity photons[3]. Driven direct two-qubit gates are expected in the dispersive regime[4], and provide a means of universal quantum computation. However, simulating a Toffoli gate, a necessary operation for scaling, with this limited tool box requires at least five two-qubit operations[5]. Here we propose a scheme for generating single-shot three-qubit entanglement in an all-to-all geometry using an electrically controlled ac magnetic field.

[1] G. Burkard et al., Rev. Mod. Phys. 95, 025003 (2023)

[2] N. M. Linke et al., Proc. Nat. Acad. Sci. 114, 3305 (2017)

[3] P. Harvey-Collard et al., Phys. Rev. X 12, 021026 (2022)

[4] S. R. McMillan et al., Phys. Rev. B 108, 125414 (2023)

[5] N. Yu, et al., Phys. Rev. A 88, 010304(R) (2013)