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This work is on a user-friendly reduced basis method for solving a family of parametric PDEs by preconditioned Krylov subspace methods including the conjugate gradient method, generalized minimum residual method, and bi-conjugate gradient…

Numerical Analysis · Mathematics 2026-02-24 Yuwen Li , Ludmil T. Zikatanov , Cheng Zuo

We study stochastic optimization algorithms for constrained nonconvex stochastic optimization problems with Markovian data. In particular, we focus on the case when the transition kernel of the Markov chain is state-dependent. Such…

Optimization and Control · Mathematics 2022-11-10 Abhishek Roy , Krishnakumar Balasubramanian , Saeed Ghadimi

Quantum Krylov subspace diagonalization is a prominent candidate for early fault tolerant quantum simulation of many-body and molecular systems, but so far the focus has been mainly on computing ground-state energies. We go beyond this by…

The $\mathcal{H}_2$ model reduction problem for high-dimensional linear quantum systems is studied under the constraint of physical realizability (PR). This constraint requires preservation of the canonical commutation relations and the…

Quantum Physics · Physics 2026-05-11 Alfo Borzi , Guofeng Zhang

Neural-network quantum states (NQS) employ artificial neural networks to encode many-body wave functions in second quantization through variational Monte Carlo (VMC). They have recently been applied to accurately describe electronic wave…

Chemical Physics · Physics 2023-11-27 Xiang Li , Jia-Cheng Huang , Guang-Ze Zhang , Hao-En Li , Chang-su Cao , Dingshun Lv , Han-Shi Hu

We present a novel data-driven reformulation of the iterative SVD-rational Krylov algorithm (ISRK), in its original formulation a Petrov-Galerkin (two-sided) projection-based iterative method for model reduction combining rational Krylov…

Numerical Analysis · Mathematics 2024-07-19 Ion Victor Gosea , Serkan Gugercin , Christopher Beattie

Quantum reservoir computing algorithms recently emerged as a standout approach in the development of successful methods for the NISQ era, because of its superb performance and compatibility with current quantum devices. By harnessing the…

Drawing the quantum phase diagram of a many-body system in the parameter space of its Hamiltonian can be seen as a learning problem, which implies labelling the corresponding ground states according to some classification criterium that…

Quantum Physics · Physics 2025-10-17 Mehran Khosrojerdi , Alessandro Cuccoli , Paola Verrucchi , Leonardo Banchi

Quantum simulation of complex many-body systems beyond classical computational capabilities provides a promising route toward understanding novel quantum phases and their transitions. In particular, analog quantum simulators with global…

Quantum Physics · Physics 2026-05-11 Shuo Zhang , Yuzhi Tong , Pengfei Zhang , Zeyu Liu

MRChem is a code for molecular electronic structure calculations, based on a multiwavelet adaptive basis representation. We provide a description of our implementation strategy and several benchmark calculations. Systems comprising more…

The prospect of quantum solutions for complicated optimization problems is contingent on mapping the original problem onto a tractable quantum energy landscape, e.g. an Ising-type Hamiltonian. Subsequently, techniques like adiabatic…

Quantum Physics · Physics 2025-10-17 Sebastian Egginger , Kristina Kirova , Sonja Bruckner , Stefan Hillmich , Richard Kueng

Machine learning (ML) holds great promise for extracting insights from complex quantum many-body data obtained in quantum experiments. This approach can efficiently solve certain quantum problems that are classically intractable, suggesting…

Quantum Physics · Physics 2025-09-18 Koki Chinzei , Quoc Hoan Tran , Norifumi Matsumoto , Yasuhiro Endo , Hirotaka Oshima

In this paper, we present a quantum algorithm for approximating multivariate traces, i.e. the traces of matrix products. Our research is motivated by the extensive utility of multivariate traces in elucidating spectral characteristics of…

Quantum Physics · Physics 2024-05-03 Liron Mor Yosef , Shashanka Ubaru , Lior Horesh , Haim Avron

Quantum reservoir computing (QRC) is a low-complexity learning paradigm that combines the inherent dynamics of input-driven many-body quantum systems with classical learning techniques for nonlinear temporal data processing. Optimizing the…

Quantum Physics · Physics 2025-07-30 Moein N. Ivaki , Achilleas Lazarides , Tapio Ala-Nissila

Neural-network quantum states (NQS) offer a versatile and expressive alternative to traditional variational ans\"atze for simulating physical systems. Energy-based frameworks, like Hopfield networks and Restricted Boltzmann Machines,…

Quantum Physics · Physics 2024-12-18 Manas Sajjan , Vinit Singh , Sabre Kais

One way to approximate a quantum annealing schedule is to use multiple quantum walks chained together, without intermediate measurements, to produce a multi-stage quantum walk (MSQW). Previous work has shown that a MSQW is better than QAOA…

Quantum Physics · Physics 2026-05-27 Asa Hopkins , Viv Kendon

Quantum computing architectures require an accurate and efficient description in terms of many-electron states. Recent implementations include quantum dot arrays, where the ground state of a multi q-bit system can be altered by voltages…

Mesoscale and Nanoscale Physics · Physics 2022-09-27 G. A. Nemnes , T. L. Mitran , A. T. Preda , I. Ghiu , M. Marciu , A. Manolescu

Quantum algorithms require accurate representations of electronic states on a quantum device, yet the approximation of electronic wave functions for strongly correlated systems remains a profound theoretical challenge, with existing methods…

Quantum Physics · Physics 2025-04-29 Dipanjali Halder , Dibyendu Mondal , Rahul Maitra

We present a technique for optimizing hundreds of thousands of variational parameters in variational quantum Monte Carlo. By introducing iterative Krylov subspace solvers and by multiplying by the Hamiltonian and overlap matrices as they…

Strongly Correlated Electrons · Physics 2013-05-30 Eric Neuscamman , C. J. Umrigar , Garnet Kin-Lic Chan

Quantum many-body control is among most challenging problems in quantum science, due to computational complexity of related underlying problems. We propose an efficient approach for solving a class of control problems for many-body quantum…

Quantum Physics · Physics 2024-02-21 I. A. Luchnikov , M. A. Gavreev , A. K. Fedorov