Variational Quantum Algorithms (VQAs) are critically threatened by the Barren Plateau (BP) phenomenon. In this work, we introduce the H-EFT Variational Ansatz (H-EFT-VA), an architecture inspired by Effective Field Theory (EFT). By enforcing a hierarchical "UV-cutoff" on initialization, we theoretically restrict the circuit's state exploration, preventing the formation of approximate unitary 2-designs. We provide a rigorous proof that this localization guarantees an inverse-polynomial lower bound on the gradient variance: $Var[\partial θ] \in Ω(1/poly(N))$. Crucially, unlike approaches that avoid BPs by limiting entanglement, we demonstrate that H-EFT-VA maintains volume-law entanglement and near-Haar purity, ensuring sufficient expressibility for complex quantum states. Extensive benchmarking across 16 experiments -- including Transverse Field Ising and Heisenberg XXZ models -- confirms a 109x improvement in energy convergence and a 10.7x increase in ground-state fidelity over standard Hardware-Efficient Ansatze (HEA), with a statistical significance of $p < 10^{-88}$.

翻译：变分量子算法（VQAs）正受到贫瘠高原（BP）现象的严重威胁。本工作提出了H-EFT变分拟设（H-EFT-VA），这是一种受有效场论（EFT）启发的架构。通过在初始化时强制执行分层“紫外截断”，我们从理论上限制了电路的态空间探索，防止了近似酉2-设计的形成。我们严格证明了这种局域化保证了梯度方差具有逆多项式下界：$Var[\partial θ] \in Ω(1/poly(N))$。至关重要的是，与通过限制纠缠来避免BP的方法不同，我们证明了H-EFT-VA保持了体积律纠缠和近Haar纯度，从而确保了对复杂量子态的足够表达能力。在16项实验（包括横场伊辛模型和海森堡XXZ模型）上的广泛基准测试证实，相较于标准的硬件高效拟设（HEA），其能量收敛性提升了109倍，基态保真度提高了10.7倍，统计显著性为$p < 10^{-88}$。