  Electrostatically defined quantum dot arrays offer a compelling platform for
quantum computation and simulation. However, tuning up such arrays with
existing techniques becomes impractical when going beyond a handful of quantum
dots. Here, we present a method for systematically adding quantum dots to an
array one dot at a time, in such a way that the number of electrons on
previously formed dots is unaffected. The method allows individual control of
the number of electrons on each of the dots, as well as of the interdot tunnel
rates. We use this technique to tune up a linear array of eight GaAs quantum
dots such that they are occupied by one electron each. This new method
overcomes a critical bottleneck in scaling up quantum-dot based qubit
registers.
