发表机构
Center for Computation and Technology, Louisiana State University; Department of Physics, The Pennsylvania State University; Department of Physics and Astronomy, Louisiana State University（路易斯安那州立大学计算与技术中心; 宾夕法尼亚州立大学物理系; 路易斯安那州立大学物理与天文学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文将SKQD方法推广至格林函数计算，通过采样Krylov子空间和经典重叠评估，在浅电路下重构谱函数，并验证其可扩展DMFT杂质求解器的浴位点数量。
AI 中文摘要
我们将基于样本的Krylov量子对角化（SKQD）方法从基态计算推广到单粒子格林函数的评估。通过在N±1粒子数扇区中构造并采样酉Krylov子空间，并在经典上评估所有连接扇区的重叠，该方法通过Lanczos连分式重构格林函数，同时保留SKQD的浅电路、无辅助比特特性。量子设备仅需制备并采样短时演化。将该方法应用于链几何中粒子-空穴对称的单杂质安德森模型，并采用动力学平均场理论（DMFT）中使用的离散浴表示，该方法利用完整希尔伯特空间的相对较小部分恢复了谱函数。在跨越金属-绝缘体转变的一系列相互作用强度范围内，主要谱特征均被重现。这些结果表明，基于SKQD的格林函数计算可能允许在近期量子硬件上使用比当前实际可行的更多浴位点的DMFT杂质求解器。
英文摘要
We generalize the sample-based Krylov quantum diagonalization (SKQD) method from ground-state calculations to the evaluation of single-particle Green's functions. By constructing and sampling unitary Krylov subspaces in the N +/- 1 particle-number sectors and evaluating all sector-connecting overlaps classically, the approach reconstructs the Green's function via a Lanczos continued fraction while retaining the shallow-circuit, ancilla-free character of SKQD. The quantum device is required only to prepare and sample short-time evolutions. Applied to the particle-hole-symmetric single-impurity Anderson model in chain geometry, with the discrete bath representation used in dynamical mean-field theory (DMFT), the method recovers the spectral function using a relatively small fraction of the full Hilbert space. Across a range of interaction strengths that spans the metal-insulator transition, the main spectral features are reproduced. These results suggest that SKQD-based Green's-function calculations may allow DMFT impurity solvers with a larger number of bath sites on near-term quantum hardware than is currently practical.
Comments20 pages, 10 figures
