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Obtaining precise estimates of quantum observables is a crucial step of variational quantum algorithms. We consider the problem of estimating expectation values of molecular Hamiltonians, obtained on states prepared on a quantum computer.…

Quantum Physics · Physics 2020-06-30 Charles Hadfield , Sergey Bravyi , Rudy Raymond , Antonio Mezzacapo

Accurate estimation of observables in quantum systems is a central challenge in quantum information science, yet practical implementations are fundamentally constrained by the limited number of measurement shots. In this work we explore a…

Quantum Physics · Physics 2025-11-05 Keijo Korhonen , Stefano Mangini , Joonas Malmi , Hetta Vappula , Daniel Cavalcanti

Obtaining the symmetries of a model is a critical step towards developing an understanding and ultimately analytically or numerically solving the model. However, finding symmetries is generally extremely complicated, often being the result…

Simulating dynamics of physical systems is a key application of quantum computing, with potential impact in fields such as condensed matter physics and quantum chemistry. However, current quantum algorithms for Hamiltonian simulation yield…

Quantum measurements are our eyes to the quantum systems consisting of a multitude of microscopic degrees of freedom. However, the intrinsic uncertainty of quantum measurements and the exponentially large Hilbert space pose natural barriers…

Strongly Correlated Electrons · Physics 2023-04-07 Jia-Bao Wang , Yi Zhang

In this work, we consider a fundamental task in quantum many-body physics - finding and learning ground states of quantum Hamiltonians and their properties. Recent works have studied the task of predicting the ground state expectation value…

Quantum Physics · Physics 2025-01-16 Štěpán Šmíd , Roberto Bondesan

Estimating spectral gaps of quantum many-body Hamiltonians is a highly challenging computational task, even under assumptions of locality and translation-invariance. Yet, the quest for rigorous gap certificates is motivated by their broad…

Quantum Physics · Physics 2026-04-15 Kshiti Sneh Rai , Ilya Kull , Patrick Emonts , Jordi Tura , Norbert Schuch , Flavio Baccari

Solving the ground state and the ground-state properties of quantum many-body systems is generically a hard task for classical algorithms. For a family of Hamiltonians defined on an $m$-dimensional space of physical parameters, the ground…

Quantum Physics · Physics 2024-08-13 Yanming Che , Clemens Gneiting , Franco Nori

Nanoscale engineered spin systems, ranging from spins on surfaces to nanographenes, provide flexible platforms to realize entangled quantum magnets from a bottom up approach. However, assessing the quantum many-body Hamiltonian realized in…

Mesoscale and Nanoscale Physics · Physics 2025-10-22 Netta Karjalainen , Greta Lupi , Rouven Koch , Adolfo O. Fumega , Jose L. Lado

An efficient numerical method is developed using the matrix product formalism for computing the properties at finite energy densities in one-dimensional (1D) many-body localized (MBL) systems. Arguing that any efficient (possibly quantum)…

Disordered Systems and Neural Networks · Physics 2015-08-20 Yichen Huang

Standard variational methods tend to obtain upper bounds on the ground state energy of quantum many-body systems. Here we study a complementary method that determines lower bounds on the ground state energy in a systematic fashion, scales…

Quantum Physics · Physics 2015-05-28 Tillmann Baumgratz , Martin B. Plenio

Entangled quantum many-body systems can be used as sensors that enable the estimation of parameters with a precision larger than that achievable with ensembles of individual quantum detectors. Typically, the parameter estimation strategy…

Quantum Physics · Physics 2022-12-26 Yue Ban , Jorge Casanova , Ricardo Puebla

We characterize new universal features of the dynamics of chaotic quantum many-body systems, by considering a hypothetical task of "time estimation." Most macroscopic observables in a chaotic system equilibrate to nearly constant late-time…

Quantum Physics · Physics 2025-10-24 Haifeng Tang , Shreya Vardhan , Jinzhao Wang

Efficient simulation of many-body quantum systems is central to advances in physics, chemistry, and quantum computing, with a key question being whether the simulation cost scales polynomially with the system size. In this work, we analyze…

Quantum Physics · Physics 2026-03-31 Di Fang , Xiaoxu Wu , Avy Soffer

We develop an efficient and robust approach to Hamiltonian identification for multipartite quantum systems based on the method of compressed sensing. This work demonstrates that with only O(s log(d)) experimental configurations, consisting…

Quantum Physics · Physics 2015-03-13 A. Shabani , M. Mohseni , S. Lloyd , R. L. Kosut , H. Rabitz

In recent years, researchers have been exploring the applications of noisy intermediate-scale quantum (NISQ) computation in various fields. One important area in which quantum computation can outperform classical computers is the ground…

Quantum Physics · Physics 2024-01-30 Ruyu Yang , Tianren Wang , Bing-Nan Lu , Ying Li , Xiaosi Xu

We generalize effective energy variational techniques to study appropriately quantized solitonic field configurations. Our approach rests on collective quantization ideas and is specifically designed for the numerical evaluation of soliton…

High Energy Physics - Theory · Physics 2008-11-26 Sergei V. Bashinsky

Shadow estimation provides an efficient framework for estimating observable expectation values using randomized measurements. While originally developed for discrete-variable systems, its recent extensions to continuous-variable (CV)…

Quantum Physics · Physics 2025-12-16 Ruyu Yang , Xiaoming Sun , Hongyi Zhou

Predicting properties of complex, large-scale quantum systems is essential for developing quantum technologies. We present an efficient method for constructing an approximate classical description of a quantum state using very few…

Quantum Physics · Physics 2021-04-20 Hsin-Yuan Huang , Richard Kueng , John Preskill

Quantum probes that enable enhanced exploration and characterization of complex systems are central to modern science, spanning applications from biology to astrophysics and chemical design. In large many-body quantum systems, interactions…