Cryogenic Strain Cells with High-Density RF Interposers for Quantum Dot Devices

Mechanical strain is a powerful knob for engineering band structure, spin–orbit coupling, and valley physics in semiconductor qubits, yet most piezoelectric uniaxial stress cells were developed for bulk condensed-matter samples and are not natively compatible with dense microwave fan-out and cryogenic biasing required by quantum dot devices. We present a compact piezo-driven strain cell that seats an RF interposer directly above the actuators, enabling high-density DC/RF routing while applying continuously tunable strain to thick, square-profile samples typical of gate-defined quantum dot chips. The design targets state-of-the-art displacement/force ranges reported for piezo-based strain cells, while adding an interposer interface to maintain controlled impedance lines, thermal anchoring, and magnetic-field compatibility at cryogenic temperatures. This architecture bridges advances in piezo-strain apparatus for large samples with emerging cryogenic interposer technologies for scalable qubit systems, creating a practical platform to explore strain-tunable qubit parameters without compromising RF performance.