Cryogenic flip-chip interconnection for silicon qubit devices

Interfacing qubits with peripheral control circuitry poses one of the major common challenges toward realization of large-scale quantum computation. Spin qubits in silicon quantum dots (QDs)are particularly promising for scaling up, owing to the potential benefits from the know-how of the semiconductor industry. In this paper, we focus on the interposer technique as one of the potential solutions for the quantum-classical interface problem and report DC and RF characterization of a silicon QD device mounted on an interposer. We demonstrate flip-chip interconnection with the qubit device down to 4.2 K by observing Coulomb diamonds. We furthermore propose and demonstrate a laser-cut technique to disconnect peripheral circuits no longer in need. These results may pave the way toward system-on-a-chip quantum-classical integration for future quantum processors.