Cavity-mediated entanglement of parametrically driven spin qubits via sidebands*

The generation of scalable long-range entanglement represents a key outstanding challenge in realizing modular quantum information processing architectures for semiconductor spin qubits. Hybrid systems in which spins are coherently coupled to photons in a microwave cavity have enabled recent demonstrations of long-distance interactions for spin qubits in silicon. Nevertheless, tuning and scaling challenges remain for applying this approach to more than two qubits. To address these challenges, we consider a pair of quantum dot-based spin qubits that interact via microwave cavity photons, and that are also parametrically driven by separate external electric fields. For this system, we formulate a model for spin qubit entanglement in the presence of mutually off-resonant qubit and cavity frequencies. We show that the sidebands generated via the driving fields enable highly tunable qubit-qubit entanglement using only ac control and without requiring simultaneous resonance between the qubit and cavity frequencies. The model we derive can be mapped to a variety of spin qubit types. We identify experimentally relevant parameter regimes that enable the implementation of entangling gates with suppressed sensitivity to cavity photon occupation and decay. The approach we describe provides a promising route toward scalability and modularity in spin-based quantum information processing through drive-tailored gates that can be implemented in both electron and hole systems for spin-photon coupling.