  Future universal quantum computers solving problems of practical relevance
are expected to require at least $10^6$ qubits, which is a massive scale-up
from the present numbers of less than 50 qubits operated together. Out of the
different types of qubits, solid state qubits are considered to be viable
candidates for this scale-up, but interfacing to and controlling such a large
number of qubits is a complex challenge that has not been solved yet. One
possibility to address this challenge is to use qubit control circuits located
close to the qubits at cryogenic temperatures. In this work we evaluate the
feasibility of this idea, taking as a reference the physical requirements of a
two-electron spin qubit and the specifications of a standard 65 nm
complementary metal-oxide-semiconductor (CMOS) process. Using principles and
flows from electrical systems engineering we provide realistic estimates of the
footprint and of the power consumption of a complete control-circuit
architecture. Our results show that with further research it is possible to
provide scalable electrical control in the vicinity of the qubit, with our
concept.
