Two-Qubit Module Based on Phonon-Coupled Ge Hole-Spin Qubits: Design, Fabrication, and Readout at 1-4 K

• URL: http://arxiv.org/abs/2601.01704v1
• Date: Mon, 05 Jan 2026 00:46:28 GMT
• Title: Two-Qubit Module Based on Phonon-Coupled Ge Hole-Spin Qubits: Design, Fabrication, and Readout at 1-4 K
• Authors: D. -M. Mei, S. A. Panamaldeniya, K. -M. Dong, S. Bhattarai, A. Prem,
• Abstract summary: Device-level design for a two-qubit module based on phonon-coupled germanium (Ge) hole-spin qubits operating at $1$-$4mathrmK$.<n>Design integrates two gate-defined hole-spin qubits in a strained Ge quantum well with a GHz PnC defect mode that mediates a coherent phonon-based interaction.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We present a device-level design for a two-qubit module based on phonon-coupled germanium (Ge) hole-spin qubits operating at $1$-$4~\mathrm{K}$. Building on prior work on phonon-engineered Ge qubits and phononic-crystal (PnC) cavities, we specify a lithography-ready layout that integrates two gate-defined hole-spin qubits in a strained Ge quantum well with a GHz PnC defect mode that mediates a coherent phonon-based interaction. We detail the SiGe/Ge heterostructure, PnC cavity design, and a compatible nanofabrication process flow, including the gate stack, membrane patterning and release, and RF/DC wiring. We further develop a readout architecture combining spin-to-charge conversion with RF reflectometry on a proximal charge sensor, supported by a cryogenic RF chain optimized for operation at $1$-$4~\mathrm{K}$. Finally, we outline the cryogenic measurement environment, tuning procedures, and a stepwise benchmarking program targeting single-qubit control, phonon-bandgap suppression of relaxation channels, and resolvable phonon-mediated two-qubit coupling. The resulting module provides a scalable template for medium-range coupling of Ge hole-spin qubits and connects materials and phonon engineering with circuit-level readout, enabling future experimental demonstrations of entangling gates, Bell-state generation, and phonon-enabled quantum sensing.

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