Deterministic Ground State Preparation via Power-Cosine Filtering of Time Evolution Operators

• URL: http://arxiv.org/abs/2602.19556v1
• Date: Mon, 23 Feb 2026 07:01:30 GMT
• Title: Deterministic Ground State Preparation via Power-Cosine Filtering of Time Evolution Operators
• Authors: Jeongbin Jo,
• Abstract summary: We propose a non-variational protocol for ground state preparation using a Power-Cosine quantum signal processing filter.<n>By eschewing complex block-encoding techniques, our method directly utilizes coherent time-evolution operators controlled by a single ancillary qubit.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: The deterministic preparation of quantum many-body ground states is essential for advanced quantum simulation, yet optimal algorithms often require prohibitive hardware resources. Here, we propose a highly efficient, non-variational protocol for ground state preparation using a Power-Cosine quantum signal processing (QSP) filter. By eschewing complex block-encoding techniques, our method directly utilizes coherent time-evolution operators controlled by a single ancillary qubit. The integration of mid-circuit measurement and reset (MCMR) drastically minimizes spatial overhead, translating iterative non-unitary filtering into deep temporal coherence. We analytically demonstrate that this approach achieves exponential suppression of excited states with a circuit depth scaling of $\mathcal{O}(Δ^{-2}\log(1/ε))$, prioritizing implementational simplicity over optimal asymptotic complexity. Numerical simulations on the 1D Heisenberg XYZ model validate the theoretical soundness and shot-noise resilience of our method. Furthermore, an advantage analysis reveals that our protocol exponentially outperforms standard Trotterized Adiabatic State Preparation (TASP) at equivalent circuit depths. This single-ancilla framework provides a highly practical and deterministic pathway for many-body ground state preparation on Early Fault-Tolerant (EFT) quantum architectures.

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