Electrostatic coupling control of two-gate metal levels CMOS-based quantum dots*

Recent demonstrations of high-fidelity gates using CMOS-based silicon quantum dots (QDs) have boosted the interest of the semiconductor industry to extend their applications to quantum computing. The importance of having individual control of the QD chemical potential and its coupling interactions (QD-QD and QD-reservoir) motivated the development of different architectures with increased number of metal levels.

In this presentation we show the versatility of QD arrays designed with two gate layers, and fabricated in a industry-compatible CMOS process. In order to show that such architectures can achieve the desired electrostatic coupling control and requested tunability, we demonstrate that we can control the transition from single to double QD regimes. Results are obtained through transport characterization. When the two QDs are tuned into a weakly-coupled regime, bias triangles are observed, as well as their excited states. Finally, we show that the tunnel-coupling control is effective in accumulation mode, where the QDs can be formed at the back interface of the silicon channel. The demonstration of high electrostatic control over the coupling between the QDs is an important step towards successful manipulation of spins for qubit applications.