Simulation of Two-qubit Gate Variability and Fidelity of Spin Qubits Built on Nanosheet Technology

• URL: http://arxiv.org/abs/2606.32030v2
• Date: Wed, 01 Jul 2026 16:47:33 GMT
• Title: Simulation of Two-qubit Gate Variability and Fidelity of Spin Qubits Built on Nanosheet Technology
• Abstract summary: Low fidelity of two-qubit entanglement gates remains a key barrier to large-scale integration.<n>Recent simulations of silicon spin-qubit two-qubit gates have been performed on silicon-on-insulator platforms.<n>Nanosheet-based charge-qubit work has been limited to single-qubit operation.
• Score: 0.7009487789080343
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Silicon spin qubits are promising for large-scale quantum-computer integration because they can fully leverage the well-developed semiconductor infrastructure. However, the low fidelity of two-qubit entanglement gates remains a key barrier to large-scale integrations. Recent simulations of silicon spin-qubit two-qubit gates have been performed on silicon-on-insulator (SOI) platforms, while nanosheet-based charge-qubit work has been limited to single-qubit operation using a two-dimensional Schrödinger approximation. In this work, we study silicon spin-qubit double quantum dots built on nanosheet technology using the Quantum Technology Computer-Aided Design (QTCAD) simulation suite to run three-dimensional Poisson and Schroedinger solvers, followed by a many-body solver to extract exchange interactions. We evaluate the exchange energy sensitivity to process and bias variations and then use QuTiP to solve the master equation for a two-qubit gate. The results show that millivolt-level bias variations at the plunger and middle barrier gates can reduce the gate fidelity below 99%, a common threshold target for many fault-tolerant quantum-computing algorithms. Gate-referred 1/f charge-noise effects are also analyzed through the resulting coherence time.

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