Article
Physics, Multidisciplinary
Aaram J. Kim, Katharina Lenk, Jiajun Li, Philipp Werner, Martin Eckstein
Summary: We propose a diagrammatic Monte Carlo approach for quantum impurity models, which is a generalization of the strong-coupling expansion for fermionic impurity models. The algorithm is based on a self-consistently computed three-point vertex and a stochastically sampled four-point vertex and provides numerically exact results in a wide parameter regime. The performance of the algorithm is demonstrated with applications to a spin-boson model representing an emitter in a waveguide. The spatial distribution of the photon density around the emitter is also discussed.
PHYSICAL REVIEW LETTERS
(2023)
Article
Mathematics, Applied
Zhenning Cai, Geshuo Wang, Siyao Yang
Summary: We propose two diagrammatic Monte Carlo methods for describing quantum systems coupled with harmonic baths, which are governed by integro-differential equations. The first method is a reformulation of the Dyson series, and the second method, called "boldthin-bold diagrammatic Monte Carlo," employs diagram resummation to accelerate convergence. These methods exploit the recurrence relation of path integrals, which is the most computationally intensive part of the numerical methods. Compared to previous algorithms, our methods incorporate the reuse of system-associated functionals and demonstrate improved computational efficiency and memory cost. Numerical experiments in the spin-boson model validate the effectiveness of the proposed methods.
SIAM JOURNAL ON SCIENTIFIC COMPUTING
(2023)
Article
Physics, Multidisciplinary
Aaram J. Kim, Nikolay Prokof'ev, Boris Svistunov, Evgeny Kozik
Summary: The major obstacle for Feynman diagrammatic expansions to accurately solve many-fermion systems in strongly correlated regimes is the slow convergence or divergence problem. Different techniques have been proposed to address this issue, with the homotopic action providing a universal and systematic framework for unifying existing and generating new methods.
PHYSICAL REVIEW LETTERS
(2021)
Article
Computer Science, Interdisciplinary Applications
Corey Melnick, Patrick Semon, Kwangmin Yu, Nicholas D'Imperio, Andre-Marie Tremblay, Gabriel Kotliar
Summary: ComCTQMC is a GPU-accelerated quantum impurity solver that efficiently measures various observables and can solve complex-valued impurity problems. It demonstrates significant acceleration in large Hilbert spaces but may offer less impressive results or even deceleration in simpler problems. The solver employs improved estimators and reduced density matrices to enhance observable measurements.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Engineering, Petroleum
F. Cala, E. Nunez, N. Bahamon, J. A. Fuentes
Summary: A comparison was made between uncertainty assessments using the GUM framework and the Monte Carlo method, confirming the adequacy of the GUM method for liquid hydrocarbon measurements with a vertical fixed-top tank and a positive displacement meter. The maximum differences between GUM and MCM uncertainties were found to be within acceptable tolerance levels for both examples.
Article
Materials Science, Multidisciplinary
Matthew R. Carbone, David R. Reichman, John Sous
Summary: The study generalizes the family of approximate momentum average methods to formulate an efficient algorithm for computing the Green's function of particles dressed by bosons, demonstrating superior performance and potential for extension to different physical scenarios. The approach is successfully applied to several important models in solids and molecular complexes, showcasing its ability to provide exact numerical results in extreme adiabatic limits.
Article
Materials Science, Multidisciplinary
G. Bouzerar
Summary: Research shows that flat bands in two-dimensional materials can pave the way for room-temperature ferromagnetism in 2D compounds. The magnetic exchanges between localized spins are largely dominated by the ferromagnetic contribution of the flat bands, and the crossover temperatures (ferromagnetic/paramagnetic phase transition) scale linearly with the local coupling, leading to temperatures higher by an order of magnitude compared to current experimental reports. High crossover temperatures could be achieved in micrometer-sized flat band systems.
Article
Chemistry, Multidisciplinary
Daejin Kim, Suji Lee, Hohyun Jung
Summary: In this paper, the time-dependent ability of workers participating in distributed matrix-vector multiplication over heterogeneous clusters is estimated. The workers' ability is modeled as a latent variable, and a log-normally distributed working rate is introduced as a function of the latent variable. The estimation and inference on the working rates are effective in reducing expected latency, as observed from simulations.
APPLIED SCIENCES-BASEL
(2023)
Article
Chemistry, Physical
Takashi Tsuchimochi, Yoohee Ryo, Seiichiro L. Ten-no, Kazuki Sasasako
Summary: In this study, several improvements are made to the Quantum Imaginary Time Evolution (QITE) algorithm, with a focus on molecular applications. By analyzing the derivation of the QITE equation and suggesting a theoretically grounded modification, our results demonstrate the soundness of the derived equation and its ability to better approximate imaginary time propagation. We also discuss accurately estimating the norm of an imaginary-time-evolved state and its application to excited state calculations. Additionally, the folded-spectrum QITE scheme is proposed as a straightforward extension for general excited-state simulations.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Takashi Tsuchimochi, Yoohee Ryo, Seiichiro L. Ten-no, Kazuki Sasasako
Summary: Quantum imaginary time evolution (QITE) is a hybrid algorithm that can guarantee reaching the lowest state of a system. This study improves upon QITE, specifically for molecular applications. The derivation of the QITE equation is analyzed step-by-step, and a theoretically well-founded modification is proposed. The results demonstrate the effectiveness of the derived equation, providing a better approximation for imaginary time propagation. Additionally, accurate estimation of the norm of an imaginary-time-evolved state is discussed and applied in excited state calculations using the quantum Lanczos algorithm. The folded-spectrum QITE scheme is also introduced as an extension for general excited-state simulations.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Quantum Science & Technology
Kok Chuan Tan, Dhiman Bhowmick, Pinaki Sengupta
Summary: This article proposes a quantum implementation of the Stochastic Series Expansion (SSE) Monte Carlo method, which shows significant advantages over classical implementations. In cases where classical SSE encounters the sign problem, the cost of implementing a Monte Carlo iteration scales only linearly with system size in quantum SSE, while it may scale exponentially in classical SSE. Even in cases where classical SSE is efficiently implemented, quantum SSE still offers an advantage by allowing for the measurement of more general observables.
NPJ QUANTUM INFORMATION
(2022)
Article
Chemistry, Physical
Niklas Liebermann, Khaldoon Ghanem, Ali Alavi
Summary: We investigate the exact full configuration interaction quantum Monte Carlo algorithm applied to weak sign-problem fermionic systems and show that the minimum number of walkers required is significantly reduced through an importance-sampling similarity transformation.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
J. Vucicevic, P. Stipsic, M. Ferrero
Summary: Recent advances in diagrammatic Monte Carlo methods for interacting fermions on a lattice have shown promising results by using symbolic algebra algorithms to solve internal Matsubara frequency summations of Feynman diagrams. A new approach using a closed-form analytical solution of imaginary-time integrals has demonstrated improved results and significant advantages, making the algorithm general enough for various single-time correlation function series. Tuning the action-shift in frequency-resolved manner has further improved convergence properties of the method with only a few perturbation orders, suggesting broader usage of the analytical solution in commonly used Monte Carlo algorithms.
PHYSICAL REVIEW RESEARCH
(2021)
Article
Mathematics, Applied
M. Ganesh, B. Reyes
Summary: The paper investigates a class of physical processes modeled by the Allen-Cahn (A-C) partial differential equation (PDE) evolutionary system with uncertainties in the initial state and the A-C PDE. A hybrid computational model is developed to efficiently compute statistical moments of the numerical counterparts of the A-C stochastic processes by using finite element method, high-order digital nets sampling, and interplay of discretization parameters. The hybrid framework demonstrates marked efficiency compared to standard methods in handling two- and three-dimensional space, and high stochastic dimensional A-C examples.
JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS
(2022)
Article
Physics, Fluids & Plasmas
A. A. Danshin, A. A. Kovalishin, M. Gurevich
Summary: The paper focuses on studying the nodal surfaces of wave functions for fermion systems. By using the quantum Monte Carlo method, implicit equations for nodal surfaces in s-electron systems with two to five electrons are obtained numerically. The obtained results are consistent with the findings of other researchers. The paper proposes an original method for constructing nodal surfaces that is convenient for implementing quantum Monte Carlo.
Article
Physics, Multidisciplinary
R. Rossi, N. Prokof'ev, B. Svistunov, K. Van Houcke, F. Werner
Article
Astronomy & Astrophysics
Sam Stevens, Jan Ryckebusch, Wim Cosyn, Andreas Waets
Article
Physics, Multidisciplinary
R. Rossi, T. Ohgoe, K. Van Houcke, F. Werner
PHYSICAL REVIEW LETTERS
(2018)
Article
Physics, Multidisciplinary
R. Rossi, T. Ohgoe, E. Kozik, N. Prokof'ev, B. Svistunov, K. Van Houcke, F. Werner
PHYSICAL REVIEW LETTERS
(2018)
Article
Multidisciplinary Sciences
Kevin Hoefman, Aaron Bramson, Koen Schoors, Jan Ryckebusch
Article
Astronomy & Astrophysics
Jan Ryckebusch, Wim Cosyn, Sam Stevens, Corneel Casert, Jannes Nys
Article
Multidisciplinary Sciences
Andres M. Belaza, Jan Ryckebusch, Koen Schoors, Luis E. C. Rocha, Benjamin Vandermarliere
Article
Chemistry, Analytical
Toon Bogaerts, Sylvain Watelet, Niko De Bruyne, Chris Thoen, Tom Coopman, Joris Van den Bergh, Maarten Reyniers, Dirck Seynaeve, Wim Casteels, Steven Latre, Peter Hellinckx
Summary: This paper presents an approach to monitor road conditions in real time by equipping a fleet of vehicles with sensors, using a physical road weather model to forecast future weather conditions and deliver timely warnings to drivers.
Article
Materials Science, Multidisciplinary
Kris Van Houcke, Felix Werner, Riccardo Rossi
Article
Physics, Nuclear
Jan Ryckebusch, Wim Cosyn, Tom Vieijra, Corneel Casert
Article
Materials Science, Multidisciplinary
K. Van Houcke, F. Werner, T. Ohgoe, N. Prokof'ev, B. Svistunov
Article
Optics
Senne Van Loon, Wim Casteels, Jacques Tempere
Article
Optics
Wim Casteels, Ryan M. Wilson, Michiel Wouters
Article
Optics
Mathias Van Regemortel, Wim Casteels, Iacopo Carusotto, Michiel Wouters
Article
Optics
Wim Casteels, Michiel Wouters