Efficient orthogonal control of tunnel couplings in a quantum dot array

Electrostatically defined semiconductor quantum dot arrays offer a promising platform for quantum computation and quantum simulation. However, crosstalk of gate voltages to dot potentials and inter-dot tunnel couplings complicates the tuning of the device parameters. To date, cross-talk to the dot potentials is routinely and efficiently compensated using virtual gates, but cross-talk to the tunnel barriers is currently compensated through a slow iterative process, due to exponential dependence of tunnel couplings on gate voltages. Here we show that the crosstalk on tunnel barriers can be compensated using a linear combination of gate voltages, since the exponential dependence applies to all gates. We demonstrate efficient calibration of crosstalk in a quadruple dot and define a set of virtual barrier gates as linear combinations of physical gate voltages. We then demonstrate orthogonal control of tunnel couplings in the quadruple dot using these virtual barrier gates. Our method marks a key step forward in the scalability of the tuning process of large-scale quantum dot arrays.