Scalable multi-qubit intrinsic gates in quantum dot arrays

We study the multi-qubit quantum gates intrinsic to a general array of semiconductor quantum dots and investigate how they can be implemented in a scalable way. The intrinsic quantum gates refer to the class of natural-forming transformations in the qubit rotating-frame under direct exchange coupling, and can be recognized as the instruction set of a spin-qubit chip. Adopting an perturbative treatment, we can model intrinsic gates by first-order dynamics in the coupling strength. A general formalism is developed for identifying the multi-qubit intrinsic gates under arbitrary array connectivity. Factors influencing the fidelities of the multi-qubit intrinsic gates are discussed. The advantageous applications of intrinsic gates in quantum computing and quantum error correction are explored. We also propose a theoretical scheme to overcome the problem of inhomogeneous coupling using dynamical calibration of the connecting bonds. This scheme can be further combined with periodic dynamical decoupling for robust implementations of multi-qubit gates in large-scale quantum computers.