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Quantum state tomography is the conventional method used to characterize density matrices for general quantum states. However, the data acquisition time generally scales linearly with the dimension of the Hilbert space, hindering the…

Quantum Physics · Physics 2021-07-28 Yiyu Zhou , Jiapeng Zhao , Darrick Hay , Kendrick McGonagle , Robert W. Boyd , Zhimin Shi

In this paper, a purely measurement-based method is proposed to estimate the dynamic system state matrix by applying the regression theorem of the multivariate Ornstein-Uhlenbeck process. The proposed method employs a recursive algorithm to…

Signal Processing · Electrical Eng. & Systems 2019-05-29 Hao Sheng , Xiaozhe Wang

The idea of using fragment embedding to circumvent the high computational scaling of accurate electronic structure methods while retaining high accuracy has been a long-standing goal for quantum chemists. Traditional fragment embedding…

Chemical Physics · Physics 2022-10-11 Hong-Zhou Ye , Matthew Welborn , Nathan D. Ricke , Troy Van Voorhis

Randomized measurement protocols such as classical shadows represent powerful resources for quantum technologies, with applications ranging from quantum state characterization and process tomography to machine learning and error mitigation.…

Quantum Physics · Physics 2024-06-18 Laurin E. Fischer , Timothée Dao , Ivano Tavernelli , Francesco Tacchino

Classical information loading is an essential task for many processing quantum algorithms, constituting a cornerstone in the field of quantum machine learning. In particular, the embedding techniques based on Hamiltonian simulation…

Personalized cardiac diagnostics require accurate reconstruction of myocardial displacement fields from sparse clinical imaging data, yet current methods often demand intrusive access to computational models. In this work, we apply the…

Estimating many local expectation values over time is a central measurement bottleneck in quantum simulation and device characterization. We study the task of reconstructing the Pauli-signal matrix $S_{ij}=\text{Tr}(O_i \rho(t_j))$ for a…

Quantum Physics · Physics 2026-02-16 Joseph Barreto , Daniel Lidar

In the context of state-space models, skeleton-based smoothing algorithms rely on a backward sampling step which by default has a $\mathcal O(N^2)$ complexity (where $N$ is the number of particles). Existing improvements in the literature…

Computation · Statistics 2023-03-08 Hai-Dang Dau , Nicolas Chopin

While quantum state tomography (QST) remains the gold standard for benchmarking and verifying quantum devices, it requires an exponentially large number of measurements and classical computational resources for generic quantum many-body…

Quantum Physics · Physics 2025-11-19 Zhen Qin , Casey Jameson , Alireza Goldar , Michael B. Wakin , Zhexuan Gong , Zhihui Zhu

Benchmarking the performance of quantum error correction codes in physical systems is crucial for achieving fault-tolerant quantum computing. Current methodologies, such as (shadow) tomography or direct fidelity estimation, fall short in…

Quantum Physics · Physics 2024-10-17 Junjie Chen , Pei Zeng , Qi Zhao , Xiongfeng Ma , You Zhou

Classical shadow tomography provides a randomized scheme for approximating the quantum state and its properties at reduced computational cost with applications in quantum computing. In this Letter we present an algorithm for realizing fewer…

Quantum Physics · Physics 2023-12-20 Irma Avdic , David A. Mazziotti

We have applied the momentum space version of the Density Matrix Renormalization Group method ($k$-DMRG) in quantum chemistry in order to study the accuracy of the algorithm in the new context. We have shown numerically that it is possible…

Strongly Correlated Electrons · Physics 2009-02-06 O. Legeza , J. Roder , B. A. Hess

Cosmological information from forthcoming galaxy surveys, such as LSST and Euclid, will soon exceed that available from the CMB. Higher order correlation functions, like the bispectrum, will be indispensable for realising this potential.…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-06 Johnathan Hung , James R. Fergusson , E. P. S. Shellard

We present a robust shadow estimation protocol for wide classes of low-depth measurement circuits that mitigates noise as long as the effective measurement map including noise is locally unitarily invariant. This is in practice an excellent…

Quantum Physics · Physics 2025-03-26 Renato M. S. Farias , Raghavendra D. Peddinti , Ingo Roth , Leandro Aolita

We investigate fully self-consistent multiscale quantum-classical algorithms on current generation superconducting quantum computers, in a unified approach to tackle the correlated electronic structure of large systems in both quantum…

Differential phase contrast (DPC) imaging plays an important role in the family of quantitative phase measurement. However, the reconstruction algorithm for quantitative DPC (qDPC) imaging is not yet optimized, as it does not incorporate…

Optimization and Control · Mathematics 2022-06-16 Shuhe Zhang , Tao Peng , Zeyu Ke , Meng Shao , Tos T. J. M. Berendschot , Jinhua Zhou

We study quantum sparse recovery in non-orthogonal, overcomplete dictionaries: given coherent quantum access to a state and a dictionary of vectors, the goal is to reconstruct the state up to $\ell_2$ error using as few vectors as possible.…

Quantum Physics · Physics 2025-10-09 Armando Bellante , Stefano Vanerio , Stefano Zanero

Shadow tomography aims to build a classical description of a quantum state from a sequence of simple random measurements. Physical observables are then reconstructed from the resulting classical shadow. Shadow protocols which use…

Quantum Physics · Physics 2024-08-14 Sumner N. Hearth , Michael O. Flynn , Anushya Chandran , Chris R. Laumann

We present and test a protocol to learn the matrix-product operator (MPO) representation of an experimentally prepared quantum state. The protocol takes as an input classical shadows corresponding to local randomized measurements, and…

The molecular dark state participates in many important photon-induced processes, yet is typically beyond the optical-spectroscopic measurement due to the forbidden transition dictated by the selection rule. In this work, we propose to use…

Quantum Physics · Physics 2021-11-09 Guohui Dong , Zhubin Hu , Xiang Sun , Hui Dong