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Quantum algorithms exploiting real-time evolution under a target Hamiltonian have demonstrated remarkable efficiency in extracting key spectral information. However, the broader potential of these methods, particularly beyond ground state…

Among recent insights into learning quantum states, online learning and shadow tomography procedures are notable for their ability to accurately predict expectation values even of adaptively chosen observables. In contrast to the state…

Quantum Physics · Physics 2024-06-07 Asad Raza , Matthias C. Caro , Jens Eisert , Sumeet Khatri

We extend correlated sampling from classical auxiliary-field quantum Monte Carlo to the quantum-classical (QC-AFQMC) framework, enabling accurate nuclear force computations crucial for geometry optimization and reaction dynamics. Stochastic…

Classifying phase transitions is a fundamental and complex challenge in condensed matter physics. This work proposes a framework for identifying quantum phase transitions by combining classical shadows with unsupervised machine learning. We…

Learning properties of quantum states from measurement data is a fundamental challenge in quantum information. The sample complexity of such tasks depends crucially on the measurement primitive. While shadow tomography achieves…

Quantum Physics · Physics 2025-10-10 Jan Nöller , Viet T. Tran , Mariami Gachechiladze , Richard Kueng

Quantum process tomography (QPT) is crucial for advancing quantum technologies, including quantum computers, quantum networks and quantum sensors. Shadow process tomography (SPT) utilizes the Choi isomorphism to map QPT to shadow state…

Quantum Physics · Physics 2025-07-16 Haigang Wang , Kan He

Analog quantum simulation is an essential routine for quantum computing and plays a crucial role in studying quantum many-body physics. Typically, the quantum evolution of an analog simulator is largely determined by its physical…

Quantum Physics · Physics 2024-03-18 Zhenhuan Liu , Zihan Hao , Hong-Ye Hu

We present shadow spectroscopy as a simulator-agnostic quantum algorithm for estimating energy gaps using very few circuit repetitions (shots) and no extra resources (ancilla qubits) beyond performing time evolution and measurements. The…

Quantum Physics · Physics 2025-04-10 Hans Hon Sang Chan , Richard Meister , Matthew L. Goh , Bálint Koczor

In this article we develop a continuous variable (CV) shadow tomography scheme with wide ranging applications in quantum optics. Our work is motivated by the increasing experimental and technological relevance of CV systems in quantum…

Quantum Physics · Physics 2024-05-03 Simon Becker , Nilanjana Datta , Ludovico Lami , Cambyse Rouzé

Simulating the dynamics of complex quantum systems is a central application of quantum devices. Here, we propose leveraging the power of measurements to simulate short-time quantum dynamics of physically prepared quantum states in classical…

Quantum Physics · Physics 2025-07-02 Paul K. Faehrmann , Jens Eisert , Maria Kieferova , Richard Kueng

In Loop Quantum Gravity, the quantum action of the volume operator is crucial in understanding quantum dynamics. In this work, we implement a generalized numerical algorithm that can compute the quantum action of the volume operator on a…

General Relativity and Quantum Cosmology · Physics 2026-04-01 Haida Li , Hongguang Liu

Properties of quantum systems can be estimated using classical shadows, which implement measurements based on random ensembles of unitaries. Originally derived for global Clifford unitaries and products of single-qubit Clifford gates,…

Quantum Physics · Physics 2023-09-25 Mirko Arienzo , Markus Heinrich , Ingo Roth , Martin Kliesch

Although quantum machine learning has shown great promise, the practical application of quantum computers remains constrained in the noisy intermediate-scale quantum era. To take advantage of quantum machine learning, we investigate the…

Quantum Physics · Physics 2026-02-20 Shaozhi Li , M Sabbir Salek , Mashrur Chowdhury , Yao Wang

Quantum learning encounters fundamental challenges when estimating non-linear properties, owing to the inherent linearity of quantum mechanics. Although recent advances in single-copy randomized measurement protocols have achieved optimal…

Quantum Physics · Physics 2026-03-30 Zhenyu Du , Yifan Tang , Andreas Elben , Ingo Roth , Jens Eisert , Zhenhuan Liu

We introduce an improved one-shot characterisation of randomness extraction against quantum side information (privacy amplification), strengthening known one-shot bounds and providing a unified derivation of the tightest known asymptotic…

Quantum Physics · Physics 2026-04-07 Bartosz Regula , Marco Tomamichel

Quantum state tomography (QST) remains the prevailing method for benchmarking and verifying quantum devices; however, its application to large quantum systems is rendered impractical due to the exponential growth in both the required number…

Quantum Physics · Physics 2025-01-10 Zhen Qin , Joseph M. Lukens , Brian T. Kirby , Zhihui Zhu

Motivated by a similar approach for Born-Oppenheimer molecular dynamics, this paper proposes an extended "shadow" Lagrangian density for quantum states of superfluids. The extended Lagrangian contains an additional field variable that is…

Numerical Analysis · Mathematics 2021-01-13 Patrick Henning , Anders M. N. Niklasson

We combine classical heuristics with partial shadow tomography to enable efficient protocols for extracting information from correlated ab initio electronic systems encoded on quantum devices. By proposing the use of a correlation energy…

We provide a general machine learning methodology that integrates classical shadow representations with unsupervised principal component analysis (PCA) to explore various quantum phase transitions. By sampling spin configurations from…

Quantum Physics · Physics 2026-04-22 Chi-Ting Ho , Daw-Wei Wang

We propose a tomographic protocol for estimating any $ k $-body reduced density matrix ($ k $-RDM) of an $ n $-mode fermionic state, a ubiquitous step in near-term quantum algorithms for simulating many-body physics, chemistry, and…

Quantum Physics · Physics 2022-10-04 Andrew Zhao , Nicholas C. Rubin , Akimasa Miyake
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