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Exponential quantum advantages in learning quantum observables from classical data 指数量子在从经典数据中学习量子可观测值方面的优势
IF 7.6 1区 物理与天体物理 Q1 PHYSICS, APPLIED Pub Date : 2026-01-10 DOI: 10.1038/s41534-025-01162-2
Riccardo Molteni, Casper Gyurik, Vedran Dunjko
Quantum computers are believed to bring computational advantages in simulating quantum many-body systems. However, recent works have shown that classical machine learning algorithms are able to predict numerous properties of quantum systems with classical data. Despite examples of learning tasks with provable quantum advantages being proposed, they all involve cryptographic functions and do not represent any physical scenarios encountered in laboratory settings. In this paper, we prove quantum advantages for the physically relevant task of learning quantum observables from classical (measured-out) data. We consider two types of observables: first, we prove a learning advantage for linear combinations of Pauli strings, then we extend our results to a broader case of unitarily parametrized observables. For each case, we delineate sharp boundaries separating physically relevant tasks that admit efficient classical learning from those for which a quantum computer remains necessary for data analysis. Unlike previous works, our classical hardness results rely only on the weaker assumption that $$BQP$$ B Q P hard processes cannot be simulated by polynomial-size classical circuits, and we also provide a nontrivial quantum learning algorithm. Our results clarify when quantum resources are useful for learning problems in quantum many-body physics, and suggest practical directions in which quantum learning improvements may emerge.
量子计算机被认为在模拟量子多体系统方面具有计算优势。然而,最近的研究表明,经典的机器学习算法能够用经典数据预测量子系统的许多特性。尽管提出了具有可证明的量子优势的学习任务示例,但它们都涉及加密功能,并且不代表在实验室环境中遇到的任何物理场景。在本文中,我们证明了量子在从经典(测量)数据中学习量子可观测物的物理相关任务中的优势。我们考虑两种类型的可观察对象:首先,我们证明了泡利弦线性组合的学习优势,然后我们将我们的结果扩展到更广泛的单参数化可观察对象的情况。对于每种情况,我们都划定了明确的界限,将物理相关的任务区分开来,这些任务允许有效的经典学习,而量子计算机仍然需要进行数据分析。与以前的工作不同,我们的经典硬度结果仅依赖于一个较弱的假设,即$$BQP$$ B Q P硬过程不能被多项式大小的经典电路模拟,并且我们还提供了一个非平凡的量子学习算法。我们的研究结果阐明了量子资源何时对量子多体物理中的学习问题有用,并提出了量子学习改进可能出现的实际方向。
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引用次数: 0
Few-shot estimation of entanglement with Bell measurement assistance 用贝尔测量辅助的少射估计纠缠
IF 7.6 1区 物理与天体物理 Q1 PHYSICS, APPLIED Pub Date : 2026-01-09 DOI: 10.1038/s41534-025-01172-0
Gong-Chu Li, Lei Chen, Xu-Song Hong, Si-Qi Zhang, Huaqing Xu, Yuancheng Liu, You Zhou, Geng Chen, Chuan-Feng Li, Guang-Can Guo
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引用次数: 0
Non-Gaussian state preparation and enhancement using weak-value amplification 利用弱值放大制备和增强非高斯态
IF 7.6 1区 物理与天体物理 Q1 PHYSICS, APPLIED Pub Date : 2026-01-08 DOI: 10.1038/s41534-025-01176-w
Xiao-Xi Yao, Yusuf Turek
We introduce a protocol for generating non-Gaussian (nG) states via postselected weak measurement. The scheme involves injecting an arbitrary quantum state and a single photon into the signal and idler ports of an interferometer with a third-order nonlinear medium. An nG state is conditionally produced at the signal output, heralded by single-photon detection in an idler output channel. The protocol exploits a weak cross-Kerr interaction, with effective single-photon nonlinearity enhanced by weak-value amplification. By tuning the weak value of the idler photon number operator within experimentally feasible parameters, diverse nG states can be generated with high fidelity. Specific examples include photon-added coherent states, displaced and squeezed number states, and intermediate nG states from coherent and squeezed vacuum inputs. Furthermore, the protocol enables enhancement of non-Gaussianity and enlargement of Schrödinger cat (SC) states when ideal SC states are used as input. Our results provide an alternative route for conditional generation of tunable nG states, with potential applications in quantum information processing and state engineering.
我们介绍了一种通过后选弱测量产生非高斯态(nG)的协议。该方案涉及将任意量子态和单个光子注入具有三阶非线性介质的干涉仪的信号和空闲端口。在信号输出处有条件地产生一个nG态,由空闲输出通道中的单光子检测预示。该协议利用弱交叉克尔相互作用,通过弱值放大增强有效的单光子非线性。通过在实验可行的参数范围内调整空闲光子数算子的弱值,可以高保真地生成不同的nG态。具体的例子包括光子加入相干态,位移和压缩数态,以及相干和压缩真空输入的中间nG态。此外,当使用理想SC状态作为输入时,该协议可以增强非高斯性并扩大Schrödinger cat (SC)状态。我们的研究结果为条件生成可调nG状态提供了另一种途径,在量子信息处理和状态工程中具有潜在的应用前景。
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引用次数: 0
Treespilation: architecture- and state-optimised fermion-to-qubit mappings Treespilation:结构和状态优化的费米子到量子位映射
IF 7.6 1区 物理与天体物理 Q1 PHYSICS, APPLIED Pub Date : 2026-01-07 DOI: 10.1038/s41534-025-01170-2
Aaron Miller, Adam Glos, Zoltán Zimborás
Quantum computers hold great promise for efficiently simulating Fermionic systems, benefiting fields like quantum chemistry and materials science. To achieve this, algorithms typically begin by choosing a Fermion-to-qubit mapping to encode the Fermionic problem in the qubits of a quantum computer. In this work, we introduce ‘Treespilation,’ a technique for efficiently mapping Fermionic systems using a large family of favourable tree-based mappings while minimising a generic cost function to reduce quantum simulation overhead. We use this technique to minimise the number of CNOT gates required to simulate approximate chemical groundstate circuits and observe significant reductions, up to 74%, in CNOT counts on full connectivity. For devices with limited qubit connectivity, we observe similar reductions in CNOT counts, often surpassing the full connectivity CNOT count for circuits encoded with the Jordan-Wigner mapping. We observed similar reductions when applied to reducing the Pauli weight of Hubbard model Hamiltonians.
量子计算机在有效模拟费米子系统方面前景广阔,有利于量子化学和材料科学等领域。为了实现这一点,算法通常首先选择费米子到量子比特的映射,在量子计算机的量子比特中编码费米子问题。在这项工作中,我们引入了“树式映射”,这是一种使用大量有利的基于树的映射来有效映射费米子系统的技术,同时最小化通用成本函数以减少量子模拟开销。我们使用这种技术来最小化模拟近似化学基态电路所需的CNOT门的数量,并观察到完全连接时CNOT计数的显着减少,高达74%。对于具有有限量子比特连接的设备,我们观察到CNOT计数的类似减少,通常超过使用Jordan-Wigner映射编码的电路的完全连接CNOT计数。我们观察到类似的减少,当应用于减少哈伯德模型哈密顿量的泡利权时。
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引用次数: 0
Experimental demonstration of quantum continual learning with superconducting qubits 利用超导量子比特进行量子持续学习的实验论证
IF 7.6 1区 物理与天体物理 Q1 PHYSICS, APPLIED Pub Date : 2026-01-06 DOI: 10.1038/s41534-025-01174-y
Chuanyu Zhang, Zhide Lu, Liangtian Zhao, Shibo Xu, Weikang Li, Ke Wang, Jiachen Chen, Yaozu Wu, Feitong Jin, Xuhao Zhu, Yu Gao, Ziqi Tan, Zhengyi Cui, Aosai Zhang, Ning Wang, Yiren Zou, Tingting Li, Fanhao Shen, Jiarun Zhong, Zehang Bao, Zitian Zhu, Zixuan Song, Jinfeng Deng, Hang Dong, Pengfei Zhang, Wenjie Jiang, Zheng-Zhi Sun, Pei-Xin Shen, Hekang Li, Qiujiang Guo, Zhen Wang, Jie Hao, H. Wang, Dong-Ling Deng, Chao Song
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引用次数: 0
Distributed photonic variational quantum eigensolver with parameterized weak measurements 具有参数化弱测量的分布式光子变分量子本征求解器
IF 7.6 1区 物理与天体物理 Q1 PHYSICS, APPLIED Pub Date : 2026-01-03 DOI: 10.1038/s41534-025-01163-1
Donghwa Lee, Bohdan Bilash, Jaehak Lee, Hyang-Tag Lim, Yosep Kim, Seung-Woo Lee, Yong-Su Kim
We demonstrate a two-qubit variational quantum eigensolver (VQE) implementation using two spatially separated single-photon processors connected via a 3 km optical fiber network. Our approach leverages local operations on pre-shared entanglement to evaluate two-qubit Hamiltonians. By incorporating parameterized weak measurement operations within the local operations framework, we enable access to the complete Hilbert space across distributed quantum processors – a capability typically requiring complex non-local operations. Our experimental results show accurate ground state energy estimation for Hamiltonians including H-He+ cation and the Schwinger model, validating both the necessity of weak measurements and high-quality entanglement in distributed quantum computing. This work establishes a promising direction for resource-efficient, scalable quantum network architectures that maintain full computational capabilities through local operations and controlled entanglement manipulation.
我们演示了一个双量子位变分量子特征求解器(VQE)的实现,使用两个空间分离的单光子处理器通过3公里光纤网络连接。我们的方法利用预共享纠缠的局部运算来计算两个量子比特的哈密顿量。通过将参数化弱测量操作整合到局部操作框架中,我们可以跨分布式量子处理器访问完整的希尔伯特空间——这种能力通常需要复杂的非局部操作。我们的实验结果显示了包括H-He+阳离子和Schwinger模型在内的哈密顿子的精确基态能量估计,验证了分布式量子计算中弱测量和高质量纠缠的必要性。这项工作为资源高效、可扩展的量子网络架构建立了一个有前途的方向,该架构通过局部操作和受控纠缠操纵来保持完整的计算能力。
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引用次数: 0
Regeneration of spin wave in moving atoms 运动原子中自旋波的再生
IF 7.6 1区 物理与天体物理 Q1 PHYSICS, APPLIED Pub Date : 2025-12-31 DOI: 10.1038/s41534-025-01167-x
Jian-Peng Dou, Feng Lu, Xiao-Wen Shang, Hao Tang, Xian-Min Jin
In a study of amplifying atomic spin waves, we observe a nontrivial phenomenon: The spin wave stored in moving atoms has a capability of absorbing energy from an external light source, and exhibits a regeneration process. We demonstrate that this regeneration significantly enhances the lifetime and retrieval efficiency of the spin wave, while concurrently the noise is effectively suppressed. Our results suggest that the regeneration mechanism holds promise for mitigating the pronounced decoherence typically encountered in spin waves carried by room-temperature media, therefore offering potential applications in the realms of quantum information and precision measurements at ambient conditions.
在放大原子自旋波的研究中,我们观察到一个重要的现象:储存在运动原子中的自旋波具有吸收外部光源能量的能力,并表现出再生过程。结果表明,这种再生方法显著提高了自旋波的寿命和检索效率,同时有效地抑制了噪声。我们的研究结果表明,再生机制有望减轻室温介质携带的自旋波通常遇到的明显退相干,因此在量子信息和环境条件下的精确测量领域提供了潜在的应用。
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引用次数: 0
A hybrid quantum walk model unifying discrete and continuous quantum walks 统一离散和连续量子行走的混合量子行走模型
IF 7.6 1区 物理与天体物理 Q1 PHYSICS, APPLIED Pub Date : 2025-12-30 DOI: 10.1038/s41534-025-01165-z
Tianen Chen, Yun Shang
Quantum walks, both discrete and continuous, serve as fundamental tools in quantum information processing with diverse applications. This work introduces a hybrid quantum walk model that integrates the coin mechanism of discrete walks with the Hamiltonian-driven time evolution of continuous walks. Through systematic analysis of probability distributions, standard deviations, and entanglement entropy on fundamental graph structures, we reveal distinctive dynamical characteristics that differentiate our model from conventional quantum walk paradigms. The proposed framework demonstrates unifying capabilities by naturally encompassing existing quantum walk models as special cases. Two significant applications emerge from this hybrid architecture: (1) We develop a novel protocol for perfect state transfer(PST) in general connected graphs, overcoming the limitations of previous graph-specific approaches. A PST on a tree graph has been implemented on a quantum superconducting processor. (2) We devise a quantum algorithm for multiplying K adjacency matrices of n-vertex regular graphs with time complexity O(n2d1 ⋯ dK), outperforming classical matrix multiplication (O(n2.371552)) when vertex degrees di are bounded. The algorithm’s efficacy for triangle counting is experimentally validated through the quantum simulation on PennyLane. These results establish the hybrid quantum walk as a versatile framework bridging discrete and continuous paradigms while enabling practical quantum advantage in graph computation tasks.
离散和连续量子行走是量子信息处理的基本工具,具有多种应用。本文提出了一种混合量子行走模型,该模型将离散行走的硬币机制与连续行走的哈密顿驱动时间演化相结合。通过对基本图结构上的概率分布、标准差和纠缠熵的系统分析,我们揭示了将我们的模型与传统量子行走范式区分开来的独特动力学特征。所提出的框架通过自然地将现有的量子行走模型作为特殊情况包含在内,展示了统一的能力。从这种混合架构中出现了两个重要的应用:(1)我们开发了一种用于一般连接图的完美状态传输(PST)的新协议,克服了以前特定于图的方法的局限性。在量子超导处理器上实现了树形图上的PST。(2)我们设计了一种量子算法,用于乘以时间复杂度为O(n2d1⋯dK)的n顶点正则图的K个邻接矩阵,当顶点度di有界时,优于经典矩阵乘法(O(n2.371552))。通过PennyLane上的量子模拟实验验证了该算法对三角形计数的有效性。这些结果建立了混合量子行走作为一个通用框架,桥接离散和连续范式,同时在图计算任务中实现实际的量子优势。
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引用次数: 0
Modeling quantum volume using randomized benchmarking of Room-Temperature NV center quantum registers 使用室温NV中心量子寄存器的随机基准模拟量子体积
IF 7.6 1区 物理与天体物理 Q1 PHYSICS, APPLIED Pub Date : 2025-12-29 DOI: 10.1038/s41534-025-01164-0
Tom Jäger, MinSik Kwon, Max Keller, Rouven Maier, Nicholas Bronn, Regina Finsterhoelzl, Guido Burkard, Leon Büttner, Rebekka Eberle, Daniel Hähnel, Vadim Vorobyov, Jörg Wrachtrup
Accurately estimating the performance of quantum hardware is crucial for comparing different platforms and predicting the performance and feasibility of quantum algorithms and applications. In this paper, we tackle the problem of benchmarking a quantum register based on the NV center in diamond operating at room temperature. We define the connectivity map as well as single-qubit performance. Thanks to an all-to-all connectivity, the 2 and 3-qubit gates performance is promising and competitive among other platforms. We experimentally calibrate the error model for the register and use it to estimate the quantum volume, a metric used for quantifying the quantum computational capabilities of the register, of 8. Our results pave the way towards the unification of different architectures of quantum hardware and the evaluation of the joint metrics.
准确估计量子硬件的性能对于比较不同平台以及预测量子算法和应用的性能和可行性至关重要。在本文中,我们解决了基于NV中心的量子寄存器在室温下运行的基准测试问题。我们定义了连通性映射以及单量子比特性能。由于全对全连接,2和3量子比特门的性能在其他平台中很有希望和竞争力。我们通过实验校准了寄存器的误差模型,并用它来估计量子体积(用于量化寄存器的量子计算能力的度量)为8。我们的研究结果为统一不同的量子硬件架构和评估联合度量铺平了道路。
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引用次数: 0
On the query complexity of unitary channel certification 关于单一通道认证查询复杂度的研究
IF 7.6 1区 物理与天体物理 Q1 PHYSICS, APPLIED Pub Date : 2025-12-29 DOI: 10.1038/s41534-025-01135-5
Sangwoo Jeon, Changhun Oh
Certifying the correct functioning of a unitary channel is a critical step toward reliable quantum information processing. In this work, we investigate the query complexity of the unitary channel certification task: testing whether a given d-dimensional unitary channel is identical to or ε-far in diamond distance from a target unitary operation. We show that incoherent algorithms—those without quantum memory—require Ω(d/ε2) queries, matching the known upper bound. In addition, for general quantum algorithms, we prove a lower bound of Omega (sqrt{d}/varepsilon )Omega (sqrt{d}/varepsilon ) and present a matching quantum algorithm based on quantum singular value transformation, establishing a tight query complexity of Theta (sqrt{d}/varepsilon )Theta (sqrt{d}/varepsilon ). On the other hand, notably, we prove that for almost all unitary channels drawn from a natural average-case ensemble, certification can be accomplished with only {mathcal{O}}(1/{varepsilon }^{2}){mathcal{O}}(1/{varepsilon }^{2}) queries. This demonstrates an exponential query complexity gap between worst- and average-case scenarios in certification, implying that certification is significantly easier for most unitary channels encountered in practice. Together, our results offer both theoretical insights and practical tools for verifying quantum processes.
验证单一信道的正确功能是实现可靠量子信息处理的关键一步。在这项工作中,我们研究了单一通道认证任务的查询复杂性:测试给定的d维单一通道与目标单一操作的钻石距离是否相同或ε-远。我们证明了非相干算法-那些没有量子存储器的算法-需要Ω(d/ε2)查询,匹配已知的上界。此外,对于一般量子算法,我们证明了Omega (sqrt{d} / varepsilon)、Omega (sqrt{d} / varepsilon)的下界,并提出了一种基于量子奇异值变换的匹配量子算法,建立了Theta (sqrt{d} / varepsilon)、Theta (sqrt{d} / varepsilon)的紧密查询复杂度。另一方面,值得注意的是,我们证明了对于从自然平均情况集合中提取的几乎所有单一通道,只需使用{mathcal{O}} (1/ {varepsilon ^}2{)}{mathcal{O}} (1/ {varepsilon ^}2{)查询即可完成认证。这表明认证中最坏情况和平均情况之间的查询复杂性差距呈指数级增长,这意味着对于实践中遇到的大多数单一通道来说,认证要容易得多。总之,我们的研究结果为验证量子过程提供了理论见解和实用工具。}
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引用次数: 0
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npj Quantum Information
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