Configuration interaction modeling of Si resonant exchange qubits for spin-photon coupling

Future platforms for scalable quantum information processing, such as spin qubits, will require the capability to entangle qubits over long physical distances. A tantalizing proposal in this space is the capacity to couple triple-quantum-dot (TQD) spin qubits via a microwave resonator. This is possible in so-called “resonant exchange” (RX) voltage regimes, wherein the system possesses a non-vanishing transverse dipole moment, giving rise to a fast spin-photon coupling rate. In this talk, we detail how numerical simulations of such regimes using configuration interaction (CI) techniques reveal qualitative insights not captured in simpler models. In particular, we show how a distinct RX regime, which we term “XRX,” may be a good candidate for real-world TQD-resonator coupling [1]. Our results demonstrate how detailed modeling of the exact multi-electron wavefunctions is critical for realistic implementation of spin-photon coupling protocols, as well as exchange operation in general.

[1] A Pan et al., “Resonant exchange operation in triple-quantum-dot qubits for spin–photon transduction,” Quantum Sci. Technol. 5 034005 (2020).