Progress Towards an Integrated Flip-Chip Quantum Dot Platform for the Rapid Characterization of Semiconductor Qubit Materials

Recent demonstrations of high fidelity multiqubit operations in semiconductor based gated lateral quantum dot (QD) qubits are often limited by fundamental properties of the materials used, and further understanding and optimization of the qubit materials is necessary. However, rapid characterization techniques for both bulk and nano-scale materials properties for QD qubits are lacking, particularly for research level groups where the initial investment of fabricating semiconductor qubits is overwhelming. We are developing a flip-chip QD platform that contains all the necessary circuit elements for the gating and readout of lateral QD qubits, which can be confined in an arbitrary material of interest without the investment of material specific fabrication techniques. A robust vacuum gap between the gates and the QD material of interest is engineered by indium bump bonding techniques with precisely etched hard stop posts and mesas. We achieve a separation of less than 100 nm with a deviation of 22 nm, which is robust to cooling to cryogenic temperatures. The proposed qubit readout scheme is dispersive gate readout via a superconducting resonator that is fabricated on the gate-side flip chip. We will present an integrated design that combines all the gating and readout elements necessary to characterize QD qubits and their host materials.