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arXiv · 2504.03149

SpinHex: A low-crosstalk, spin-qubit architecture based on multi-electron couplers

Rubén M. Otxoa·Josu Etxezarreta Martinez·Paul Schnabl·Normann Mertig·Charles Smith·Frederico Martins
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Abstract

Semiconductor spin qubits are an attractive quantum computing platform that offers long qubit coherence times and compatibility with existing semiconductor fabrication technology for scale up. Here, we propose a spin-qubit architecture based on spinless multielectron quantum dots that act as low-crosstalk couplers between a two-dimensional arrangement of spin-qubits in a hexagonal lattice. The multielectron couplers are controlled by voltage signals, which mediate fast Heisenberg exchange and thus enable coherent multi-qubit operations. For the proposed architecture, we discuss the implementation of the rotated XZZX surface code and numerically study its performance for a circuit-level noise model. We predict a threshold of $0.18\%$ for the error rate of the entangling gates. We further evaluate the scalability of the proposed architecture and predict the need for $4480$ physical qubits per logical qubit with logical error rates of $10^{-12}$ considering entangling gate fidelities of $99.99\%$, resulting in a chip size of $2.6$cm$^2$ to host $10,000$ logical qubits.

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Rubén M. Otxoa, Josu Etxezarreta Martinez, Paul Schnabl, Normann Mertig, Charles Smith, Frederico Martins. 2025-04-04. SpinHex: A low-crosstalk, spin-qubit architecture based on multi-electron couplers. https://arxiv.org/abs/2504.03149

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