Double-bracket quantum algorithms for high-fidelity ground state preparation

• URL: http://arxiv.org/abs/2408.03987v2
• Date: Thu, 06 Nov 2025 15:24:12 GMT
• Title: Double-bracket quantum algorithms for high-fidelity ground state preparation
• Abstract summary: Ground state preparation is a central application for quantum computers.<n>We investigate the performance and gate counts of double-bracket quantum algorithms (DBQAs) for ground state preparation.
• Score: 0.6832937136783648
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Ground state preparation is a central application for quantum computers but remains challenging in practice. In this work, we quantitatively investigate the performance and gate counts of double-bracket quantum algorithms (DBQAs) for ground state preparation. We propose a practical strategy in which DBQAs refine initial state preparation circuits, and we compile them for Heisenberg chains using controlled-Z and single-qubit gates. Warm-started DBQAs consistently improve both the energy and ground-state fidelity relative to the initial states provided by variational ans\"atze, indicating that DBQAs offer an effective unitary synthesis method. To demonstrate compatibility with near-term hardware, we executed a proof-of-concept example on IBM devices. With error mitigation, we observed a statistically significant improvement over the corresponding warm-start circuit. Furthermore, numerical emulations for the same system size indicate that executing DBQAs on Quantinuum's hardware could achieve similar cost-function gains without requiring error mitigation. These findings suggest that DBQAs are a promising approach for enhancing ground-state approximations on near-term quantum devices.

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