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We present a new method for modeling electronically excited states that overcomes a key failing of linear response theory by allowing the underlying ground state ansatz to relax in the presence of an excitation. The method is variational,…

Chemical Physics · Physics 2016-09-21 Eric Neuscamman

We describe a strategy to improve the efficiency of free energy estimates by reducing dissipation in nonequilibrium Monte Carlo simulations. This strategy generalizes the targeted free energy perturbation approach [Phys. Rev. E. 65, 046122,…

Statistical Mechanics · Physics 2015-05-27 Suriyanarayanan Vaikuntanathan , Christopher Jarzynski

Computation of observables in discrete stochastic, possibly conditioned, dynamics over large sparse networks is at the basis of a myriad of applications. The Matrix-Product Belief Propagation method allows a semi-analytical estimation of…

Statistical Mechanics · Physics 2026-05-15 Federico Florio , Alfredo Braunstein

Quantum Monte Carlo (QMC) methods have proven to be highly accurate for computing excited states, but the choice of optimization strategies for multiple states remains an active topic of investigation. In this work, we revisit the…

Computational Physics · Physics 2025-04-15 Stuart Shepard , Anthony Scemama , Saverio Moroni , Claudia Filippi

We develop a novel multi-configurational Symmetrized Projector Quantum Monte Carlo (MSPQMC) method to calculate excited state properties of Hubbard models. We compare the MSPQMC results for finite Hubbard chains with exact results (where…

Condensed Matter · Physics 2009-10-28 Bhargavi Srinivasan , S. Ramasesha , H. R. Krishnamurthy

There is increasing interest in quantum algorithms that are based on the imaginary-time evolution (ITE), a successful classical numerical approach to obtain ground states. However, most of the proposals so far require heavy post-processing…

Quantum Physics · Physics 2023-01-05 Pejman Jouzdani , Calvin W. Johnson , Eduardo R. Mucciolo , Ionel Stetcu

Ground-state preparation is an important task in quantum computation. The probabilistic imaginary-time evolution (PITE) method is a promising candidate for preparing the ground state of the Hamiltonian, which comprises a single ancilla…

Quantum Physics · Physics 2023-11-08 Hirofumi Nishi , Koki Hamada , Yusuke Nishiya , Taichi Kosugi , Yu-ichiro Matsushita

We present the ground state extension of the efficient quantum Monte Carlo algorithm for lattice fermions of arXiv:1411.0683. Based on continuous-time expansion of imaginary-time projection operator, the algorithm is free of systematic…

Strongly Correlated Electrons · Physics 2015-07-02 Lei Wang , Mauro Iazzi , Philippe Corboz , Matthias Troyer

This paper presents a novel approach for approximate integration over the uncertainty of noise and signal variances in Gaussian process (GP) regression. Our efficient and straightforward approach can also be applied to integration over…

Machine Learning · Statistics 2017-12-18 Ville Tolvanen , Pasi Jylänki , Aki Vehtari

Metropolis Monte Carlo simulation is a powerful tool for studying the equilibrium properties of matter. In complex condensed-phase systems, however, it is difficult to design Monte Carlo moves with high acceptance probabilities that also…

Statistical Mechanics · Physics 2014-05-27 Jerome P. Nilmeier , Gavin E. Crooks , David D. L. Minh , John D. Chodera

We propose an extension to Hawkes processes by treating the levels of self-excitation as a stochastic differential equation. Our new point process allows better approximation in application domains where events and intensities accelerate…

Machine Learning · Computer Science 2016-09-23 Young Lee , Kar Wai Lim , Cheng Soon Ong

Passive Gamma Emission Tomography (PGET) has been developed by the International Atomic Energy Agency as a way to directly image the spatial distribution of individual fuel pins in a spent nuclear fuel assembly and so determine potential…

We study real-time operator evolution using sparse Pauli dynamics, a recently developed method for simulating expectation values of quantum circuits. On the examples of energy and charge diffusion in 1D spin chains and sudden quench…

Quantum Physics · Physics 2025-04-09 Tomislav Begušić , Garnet Kin-Lic Chan

Sparse Gaussian Processes are a key component of high-throughput Bayesian optimisation (BO) loops -- an increasingly common setting where evaluation budgets are large and highly parallelised. By using representative subsets of the available…

Machine Learning · Computer Science 2022-07-14 Henry B. Moss , Sebastian W. Ober , Victor Picheny

The year 2025 marks the 100 and 30 years anniversaries of the discovery of Bose--Einstein condensation and its successful experimental realisation. Inspired by these important research achievements, a conceptually simple approach is…

Numerical Analysis · Mathematics 2026-01-28 Mechthild Thalhammer , Gregor Thalhammer-Thurner

Generating probabilistic forecasts of potential outcomes and individual treatment effects (ITE) is essential for risk-aware decision-making in domains such as healthcare, policy, marketing, and finance. We propose two novel methods: the…

Machine Learning · Computer Science 2025-09-24 Jef Jonkers , Jarne Verhaeghe , Glenn Van Wallendael , Luc Duchateau , Sofie Van Hoecke

We explain in detail how to estimate mean values and assess statistical errors for arbitrary functions of elementary observables in Monte Carlo simulations. The method is to estimate and sum the relevant autocorrelation functions, which is…

High Energy Physics - Lattice · Physics 2009-09-29 Ulli Wolff

Path integrals describing quantum many-body systems can be calculated with Monte Carlo sampling techniques, but average quantities are often subject to signal-to-noise ratios that degrade exponentially with time. A phase-reweighting…

High Energy Physics - Lattice · Physics 2017-07-12 Michael L. Wagman , Martin J. Savage

It is of interest in a variety of contexts, and in particular in the arrival time problem, to consider the quantum state obtained through unitary evolution of an initial state regularly interspersed with periodic projections onto the…

Quantum Physics · Physics 2015-05-19 J. J. Halliwell , J. M. Yearsley

With the goal to provide absolute lower bounds for the best possible running times that can be achieved by $(1+\lambda)$-type search heuristics on common benchmark problems, we recently suggested a dynamic programming approach that computes…

Neural and Evolutionary Computing · Computer Science 2021-02-24 Kirill Antonov , Maxim Buzdalov , Arina Buzdalova , Carola Doerr