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We consider finite-dimensional many-body quantum systems described by time-independent Hamiltonians and Markovian master equations, and present a systematic method for constructing smaller-dimensional, reduced models that exactly reproduce…

Quantum Physics · Physics 2025-07-30 Tommaso Grigoletto , Yukuan Tao , Francesco Ticozzi , Lorenza Viola

Numerical methods for obtaining exact dynamics of non-Markovian open quantum systems are mostly limited to either small systems or to short-time evolution only. Here, we propose a new algorithm for computing process tensors--matrix product…

Quantum Physics · Physics 2026-03-10 Émile Cochin , Jonathan Keeling , Brendon W. Lovett , Alex W. Chin

We introduce a new equation-of-motion coupled-cluster method based on a pair coupled-cluster doubles (pCCD) reference, termed frozen-pair EOM-CCSD (EOM-fpCCSD). This approach combines the computational efficiency of the pCCD ansatz with a…

Chemical Physics · Physics 2026-05-06 Katharina Boguslawski , Paweł Tecmer

Quantum embedding schemes have the potential to significantly reduce the computational cost of first principles calculations, whilst maintaining accuracy, particularly for calculations of electronic excitations in complex systems. In this…

Materials Science · Physics 2022-03-10 Joseph C. A. Prentice

We present an approach to simulate the Schr\"odinger equation through continuous time quantum walks. The CTQW-based simulation applies unitary evolution driven by a quantum walk to generate probability amplitude distributions at various…

Quantum Physics · Physics 2025-09-16 Rachana Soni , Navneet Pratap Singh

We explore the applicability of splitting methods involving complex coefficients to solve numerically the time-dependent Schr\"odinger equation. We prove that a particular class of integrators are conjugate to unitary methods for…

Numerical Analysis · Mathematics 2021-09-16 S. Blanes , F. Casas , A. Escorihuela-Tomàs

We investigate both theoretically and numerically the dynamics of Out-of-Time-Ordered Correlators (OTOCs) in quantum resonance condition for a kicked rotor model. We employ various operators to construct OTOCs in order to thoroughly…

Quantum Physics · Physics 2024-01-30 Guanling Li , Wen-Lei Zhao

We revisit the connection between equation-of-motion coupled cluster (EOM-CC) and random phase approximation (RPA) explored recently by Berkelbach [J. Chem. Phys. 149, 041103 (2018)] and unify various methodological aspects of these diverse…

Chemical Physics · Physics 2020-12-17 Varun Rishi , Ajith Perera , Rodney J. Bartlett

The reduced-density-matrix method is an promising candidate for the next generation electronic structure calculation method; it is equivalent to solve the Schr\"odinger equation for the ground state. The number of variables is the same as a…

Strongly Correlated Electrons · Physics 2011-06-27 Maho Nakata , Mituhiro Fukuda , Katsuki Fujisawa

Electronic structure methods built around double-electron excitations have a rich history in quantum chemistry. However, it seems to be the case that such methods are only suitable in particular situations and are not naturally equipped to…

Chemical Physics · Physics 2024-07-12 Zachary W. Windom , Ajith Perera , Rodney J. Bartlett

We present an efficient quantum algorithm for simulating the dynamics of Markovian open quantum systems. The performance of our algorithm is similar to the previous state-of-the-art quantum algorithm, i.e., it scales linearly in evolution…

Quantum Physics · Physics 2023-07-11 Xiantao Li , Chunhao Wang

We present a MATLAB toolbox for five different classes of exponential integrators for solving (mildly) stiff ordinary differential equations or time-dependent partial differential equations. For the efficiency of such exponential…

Numerical Analysis · Mathematics 2014-04-18 Georg Jansing

We consider the nonlinear Schr\"odinger equation with dispersion modulated by a (formal) derivative of a time-dependent function with fractional Sobolev regularity of class $W^{\alpha,2}$ for some $\alpha\in (0,1)$. Due to the loss of…

Numerical Analysis · Mathematics 2018-11-05 Martina Hofmanová , Marvin Knöller , Katharina Schratz

Density functional theory (DFT)-based simulations of materials have first-principles accuracy, but are very computationally expensive. For simulating various properties of multi-component alloys, the cluster expansion (CE) technique has…

Materials Science · Physics 2026-04-01 Jacob Jeffries , Bochuan Sun , Enrique Martinez

The unitary coupled cluster (UCC) approximation is one of the more promising wave-function ans\"atze for electronic structure calculations on quantum computers via the variational quantum eigensolver algorithm. However, for large systems…

Quantum Physics · Physics 2021-09-30 Jia Chen , Hai-Ping Cheng , James K. Freericks

In this work we develop EPOCH: Equilibrium Propagator by Orthogonal polynomial CHain, a computationally efficient method to calculate the time-dependent equilibrium Green's functions, including the anomalous Green's functions of…

Mesoscale and Nanoscale Physics · Physics 2021-09-08 Tomas Löthman , Christopher Triola , Jorge Cayao , Annica M. Black-Schaffer

The Cahn-Hilliard equation has been widely employed within various mathematical models in physics, chemistry and engineering. Explicit stabilized time stepping methods can be attractive for time integration of the Cahn-Hilliard equation,…

Numerical Analysis · Mathematics 2025-02-21 Mike A. Botchev

The continuous-time quantum walks (CTQWs) are a fundamental tool in the development of quantum algorithms. Recently, it was shown that discretizations of p-adic Schr\"odinger equations give rise to continuous-time quantum Markov chains…

Quantum Physics · Physics 2026-02-26 W. A. Zúñiga-Galindo , L. F. Chacón-Cortés

The propagator for a certain class of two time-dependent coupled and driven harmonic oscillators with time-varying angular frequencies and masses is evaluated by path integration. This is simply done through suitably chosen generalized…

Quantum Physics · Physics 2015-06-26 F. Benamira , L. Guechi

A robust and efficient time integrator for dynamical tensor approximation in the tensor train or matrix product state format is presented. The method is based on splitting the projector onto the tangent space of the tensor manifold. The…

Numerical Analysis · Mathematics 2015-05-27 Christian Lubich , Ivan Oseledets , Bart Vandereycken