  A multiscale simulation method is developed to model a quantum dot (QD) array
of germanium (Ge) holes for quantum computing. Guided by three-dimensional
numerical quantum device simulations of QD structures, an analytical model of
the tunnel coupling between the neighboring hole QDs is obtained. Two-qubit
entangling quantum gate operations and quantum circuit characteristics of the
QD array processor are then modeled. Device analysis of two-qubit Ge hole
quantum gates demonstrates faster gate speed, smaller process variability, and
less stringent requirement of feature size, compared to its silicon
counterpart. The multiscale simulation method allows assessment of the quantum
processor circuit performance from a bottom-up, physics-informed perspective.
Application of the simulation method to the Ge QD array processor indicates its
promising potential for preparing high-fidelity ansatz states in quantum
chemistry simulations.
