Sample- and Hardware-Efficient Fidelity Estimation by Stripping Phase-Dominated Magic
NextQuantum Innovation Research Center, Department of Physics and Astronomy, Seoul National University（首尔大学物理与天文学系量子创新研究中心）；Department of Physics, Korea University（高丽大学物理系）；Department of Quantum Information Science and Engineering, Sejong University（世宗大学量子信息科学与工程系）
Guedong Park, Jaekwon Chang, Yosep Kim, Yong Siah Teo, Hyunseok Jeong
备注：
(5+23) pages, 9 figures, (v2) Updated the discussion of MPS Bell sampling complexity to reflect the sharper $\mathcal{O}(nχ^3)$ scaling known in the literature; the main results and conclusions are unchanged. Added a numerical comparison with state certification and Clifford shadows
Direct fidelity estimation (DFE) is a famous tool for estimating the fidelity with a target pure state. However, such a method generally requires exponentially many sampling copies due to the large magic of the target state. This work proposes a sample- and gate-efficient fidelity estimation algorithm that is affordable within feasible quantum devices. We show that the fidelity estimation with pure states close to the structure of phase states, for which sample-efficient DFE is limited by their strong entanglement and magic, can be done by using $\mathcal{O}({\rm poly}(n))$ sampling copies, with a single $n$-qubit fan-out gate. As the target state becomes a phase state, the sampling complexity reaches $\mathcal{O}(1)$. Such a drastic improvement stems from a crucial step in our scheme, the so-called phase stripping, which can significantly reduce the target-state magic. Furthermore, we convert a complex diagonal gate resource, which is needed to design a phase-stripping-adapted algorithm, into nonlinear classical post-processing of Pauli measurements so that we only require a single fan-out gate. Additionally, as another variant using the nonlinear post-processing, we propose a nonlinear extension of the conventional DFE scheme. Here, the sampling reduction compared to DFE is also guaranteed, while preserving the Pauli measurement as the only circuit resource. We expect our work to contribute to establishing noise-resilient quantum algorithms by enabling a significant reduction in sampling overhead for fidelity estimation under the restricted gate resources, and ultimately to clarifying a fundamental gap between the resource overhead required to understand complex physical properties and that required to generate them.
Non-local Magic: closed-form solution and equivalence with magic of purification
Università degli Studi di Salerno（萨莱诺大学）；Istituto Nazionale di Fisica Nucleare (INFN)（意大利国家核物理研究所）；Scuola Superiore Meridionale（南方高等学院）；Università degli Studi di Napoli Federico II（那不勒斯费德里科二世大学）
Efficient fidelity simulation of high-rate magic distillation circuits
QuEra Computing Inc.（QuEra 计算公司）；Joint Center for Quantum Information and Computer Science, University of Maryland（马里兰大学量子信息与计算机科学联合中心）；Simons Institute for the Theory of Computing, University of California at Berkeley（加州大学伯克利分校西蒙斯计算理论研究所）；Institute for Theoretical Physics, ETH Zürich（苏黎世联邦理工学院理论物理研究所）；Department of Physics, Harvard University（哈佛大学物理学系）
Quantum computation with realistic magic state factories
容错量子计算的主要方法将很大一部分硬件专用于计算工厂，这些计算工厂生产出高保真的Ancillas，称为魔术状态。因此，高效和现实的工厂设计至关重要。在这里，我们提出了迄今为止最详细的资源评估的魔术状态工厂内的表面码量子计算机，一路上介绍了一些新技术。我们证明了Bravyi和Haah [Phys. Rev. A 86，052329（2012）]的分组码被系统地低估了;我们在数值和分析上跟踪相关误差，提供了保真度估计，而不需要联合界。我们还介绍了一个子系统代码实现这些协议的恒定时间和低辅助成本。此外，我们确认，魔术状态工厂的时空成本，规模作为一个恒定的因素的表面码成本。我们发现后经典因子分解所需的神奇状态工厂可以小到630万个数据量子位，忽略辅助量子位，假设$10^{-4}$错误门，以及长程相互作用的可用性。
Stabilizer Ranks, Barnes Wall Lattices and Magic Monotones
Institute for Quantum Computing, University of Waterloo（量子计算研究所，滑铁卢大学）；David R. Cheriton School of Computer Science, University of Waterloo（大卫·R·切里顿计算机科学学院，滑铁卢大学）；Perimeter Institute for Theoretical Physics（基础物理前沿研究所）
No-cost Bell nonlocality certification from quantum tomography and its applications in quantum-magic-resource witnessing
University of Gdańsk（格但斯克大学）；International Centre for Theory of Quantum Technologies, University of Gdańsk（格但斯克大学量子技术理论国际中心）；Max Planck Institute for Quantum Optics（马克斯·普朗克量子光学研究所）；Faculty of Physics, Ludwig Maximilian University（慕尼黑大学物理学院）；Munich Center for Quantum Science and Technology（慕尼黑量子科学与技术中心）
Hardware-Tailored Resource Estimation for Magic-State Distillation on Silicon Spin Qubits
Cavendish Lab., Department of Physics, Univ. of Cambridge（剑桥大学卡文迪什实验室物理系）；Hitachi Cambridge Lab.（日立剑桥实验室）；Department of Computer Science and Technology, Univ. of Cambridge（剑桥大学计算机科学与技术系）
Nonstabilizerness and Error Resilience in Noisy Quantum Circuits
University of Augsburg（奥格斯堡大学）；Joint Center for Quantum Information and Computer Science, NIST and University of Maryland（量子信息与计算机科学联合中心，美国国家标准与技术研究院和马里兰大学）
Experimental demonstration of non-local magic in a superconducting quantum processor
Università degli Studi di Napoli “Federico II”（那不勒斯费德里科二世大学）；Scuola Superiore Meridionale（南方高等学院）；Istituto Nazionale di Fisica Nucleare (INFN)（意大利国家核物理研究所）
Generative AI Beyond Tokens: Quantum Resource Consumption of IQP Circuits
Technical University of Applied Sciences Regensburg（雷根斯堡应用技术大学）；Universität der Bundeswehr München（联邦国防军慕尼黑大学）；Siemens AG, Foundational Technology（西门子股份公司基础技术部门）
Quantum subspace verification for error correction codes
Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University（清华大学交叉信息研究院量子信息中心）；Pritzker School of Molecular Engineering, The University of Chicago（芝加哥大学普里茨克分子工程学院）；Department of Computer Science, University of Hong Kong（香港大学计算机科学系）；Key Laboratory for Information Science of Electromagnetic Waves (Ministry of Education), Fudan University（复旦大学电磁波信息科学教育部重点实验室）
A topological theory for qLDPC: non-Clifford gates and magic state fountain on homological product codes with constant rate and beyond the $N^{1/3}$ distance barrier
