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Quantum computers are now on the brink of outperforming their classical counterparts. One way to demonstrate the advantage of quantum computation is through quantum random sampling performed on quantum computing devices. However, existing…

We design machines that learn how to rotate a quantum bit about an initially unknown direction, encoded in the state of a spin-j particle. We show that a machine equipped with a quantum memory of O(log j) qubits can outperform all machines…

Quantum Physics · Physics 2021-09-28 Yin Mo , Giulio Chiribella

We experimentally implement a machine-learning method for accurately identifying unknown pure quantum states. The method, called single-shot measurement learning, achieves the theoretical optimal accuracy for $\epsilon = O(N^{-1})$ in state…

Quantum Physics · Physics 2021-05-05 Sang Min Lee , Hee Su Park , Jinhyoung Lee , Jaewan Kim , Jeongho Bang

Quantum state readout serves as the cornerstone of quantum information processing, exerting profound influence on quantum communication, computation, and metrology. In this study, we introduce an innovative readout architecture called…

Quantum Physics · Physics 2023-12-21 Chen Ding , Xiao-Yue Xu , Shuo Zhang , Wan-Su Bao , He-Liang Huang

Quantum resources enable us to achieve an exponential advantage in learning the properties of unknown physical systems by employing quantum memory. While entanglement with quantum memory is recognized as a necessary qualitative resource,…

Quantum Physics · Physics 2026-02-26 Minsoo Kim , Changhun Oh

Quantum computing holds unparalleled potentials to enhance machine learning. However, a demonstration of quantum learning advantage has not been achieved so far. We make a step forward by rigorously establishing a noise-robust,…

Quantum Physics · Physics 2025-08-01 Haimeng Zhao , Dong-Ling Deng

Classical Shadow Tomography (Huang, Kueng and Preskill, Nature Physics 2020) is a method for creating a classical snapshot of an unknown quantum state, which can later be used to predict the value of an a-priori unknown observable on that…

Quantum Physics · Physics 2025-07-15 Zvika Brakerski , Nir Magrafta , Tomer Solomon

A fundamental task in quantum information science is to measure nonlinear functionals of quantum states, such as $\mathrm{Tr}(\rho^k O)$. Intuitively, one expects that computing a $k$-th order quantity generally requires $O(k)$ copies of…

Quantum Physics · Physics 2025-09-03 Yukun Zhang , Yusen Wu , You Zhou , Xiao Yuan

Estimating observable expectation values in eigenstates of quantum systems has a broad range of applications and is an area where early fault-tolerant quantum computers may provide practical quantum advantage. We develop a hybrid…

Quantum Physics · Physics 2026-03-03 Bence Bakó , Tenzan Araki , Bálint Koczor

Full quantum tomography of high-dimensional quantum systems is experimentally infeasible due to the exponential scaling of the number of required measurements on the number of qubits in the system. However, several ideas were proposed…

Quantum Physics · Physics 2021-01-20 G. I. Struchalin , Ya. A. Zagorovskii , E. V. Kovlakov , S. S. Straupe , S. P. Kulik

Quantum machine learning has received significant attention in recent years, and promising progress has been made in the development of quantum algorithms to speed up traditional machine learning tasks. In this work, however, we focus on…

Quantum Physics · Physics 2016-08-25 Hao-Chung Cheng , Min-Hsiu Hsieh , Ping-Cheng Yeh

Quantum state learning is a fundamental problem in physics and computer science. As near-term quantum devices are error-prone, it is important to design error-resistant algorithms. Apart from device errors, other unexpected factors could…

Quantum Physics · Physics 2025-08-20 Maryam Aliakbarpour , Vladimir Braverman , Nai-Hui Chia , Yuhan Liu

The complete learning of an $n$-qubit quantum state requires samples exponentially in $n$. Several works consider subclasses of quantum states that can be learned in polynomial sample complexity such as stabilizer states or high-temperature…

Quantum Physics · Physics 2023-09-19 Liming Zhao , Naixu Guo , Ming-Xing Luo , Patrick Rebentrost

Learning properties of quantum states and channels is known to benefit from resources such as entangled operations, auxiliary qubits, and adaptivity, whereas the resource structure of measurement learning, namely, learning properties of…

Quantum Physics · Physics 2026-02-26 Zhenhuan Liu , Qi Ye , Zhenyu Cai , Jens Eisert

Unsupervised machine learning models build an internal representation of their training data without the need for explicit human guidance or feature engineering. This learned representation provides insights into which features of the data…

Quantum Physics · Physics 2024-01-09 Felix Frohnert , Evert van Nieuwenburg

Boson sampling stands out as a promising approach toward experimental demonstration of quantum computational advantage. However, the presence of physical noise in near-term experiments hinders the realization of the quantum computational…

Quantum Physics · Physics 2025-09-30 Byeongseon Go , Changhun Oh , Hyunseok Jeong

We describe a new shadow tomography algorithm that uses $n=\Theta(\sqrt{m}\log m/\epsilon^2)$ samples, for $m$ measurements and additive error $\epsilon$, which is independent of the dimension of the quantum state being learned. This stands…

Quantum Physics · Physics 2024-11-05 Pulkit Sinha

We introduce a general statistical learning theory for processes that take as input a classical random variable and output a quantum state. Our setting is motivated by the practical situation in which one desires to learn a quantum process…

Quantum Physics · Physics 2025-02-27 Marco Fanizza , Yihui Quek , Matteo Rosati

Quantum state tomography, aimed at deriving a classical description of an unknown state from measurement data, is a fundamental task in quantum physics. In this work, we analyse the ultimate achievable performance of tomography of…

Quantifying the complexity of quantum states is a longstanding key problem in various subfields of science, ranging from quantum computing to the black-hole theory. The lower bound on quantum pure state complexity has been shown to grow…

Quantum Physics · Physics 2025-05-22 Yusen Wu , Bujiao Wu , Yanqi Song , Xiao Yuan , Jingbo B. Wang