Flip-Chip Gating of Heterostructure Quantum Materials

Semiconductor qubits are achieving circuits of greater complexity, but due to overhead requirements in fabrication, few groups have the capability to develop this technology. One approach to increase the rate of development of semiconductor-based quantum computing is to ease the barrier to entry for researchers through a simplified, yet generalized, device architecture. This, in turn, will provide faster materials characterization, currently a significant limiter in semiconductor qubits. We propose to develop a flip-chip device platform containing all control and readout elements for characterization of lateral quantum dots in materials of interest without discrimination. The gap between the chips is engineered via precise etching of mesas and hard stop posts and is attached via indium bump bonds. The proposed architecture of flip-chip-based qubit control and readout has applications in advancing to higher density quantum circuits and reducing surface preparation complexity. Progress towards achieving a flip-chip gated quantum dot with charge sensing via dispersive gate readout will be presented. We demonstrate the flip-chip gating of a Hall bar structure to qualify the fabrication process by directly comparing to a conventional fabrication-on-die process and estimate gate coupling to the quantum well.