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We describe how to implement the time-dependent variational principle for matrix product states in the thermodynamic limit for nonuniform lattice systems. This is achieved by confining the nonuniformity to a (dynamically growable) finite…

Strongly Correlated Electrons · Physics 2013-10-18 Ashley Milsted , Jutho Haegeman , Tobias J. Osborne , Frank Verstraete

The finite-element approach to lattice field theory is both highly accurate (relative errors $\sim 1/N^2$, where $N$ is the number of lattice points) and exactly unitary (in the sense that canonical commutation relations are exactly…

High Energy Physics - Theory · Physics 2016-09-06 K. A. Milton , R. Das

The accuracy of quantum dynamics simulation is usually measured by the error of the unitary evolution operator in the operator norm, which in turn depends on certain norm of the Hamiltonian. For unbounded operators, after suitable…

Quantum Physics · Physics 2021-05-26 Dong An , Di Fang , Lin Lin

Simulating the time evolution of quantum field theories given some Hamiltonian $H$ requires developing algorithms for implementing the unitary operator e^{-iHt}. A variety of techniques exist that accomplish this task, with the most common…

We show that, under certain smoothness conditions, a Brownian martingale, when evaluated at a fixed time, can be represented via an exponential formula at a later time. The time-dependent generator of this exponential operator only depends…

Probability · Mathematics 2015-10-27 Sixian Jin , Qidi Peng , Henry Schellhorn

Known as no fast-forwarding theorem in quantum computing, the simulation time for the Hamiltonian evolution needs to be $O(\|H\| t)$ in the worst case, which essentially states that one can not go across the multiple scales as the…

Quantum Physics · Physics 2025-01-30 Yonah Borns-Weil , Di Fang

We present a computationally efficient approach to solve the time-dependent Kohn-Sham equations in real-time using higher-order finite-element spatial discretization, applicable to both pseudopotential and all-electron calculations. To this…

Computational Physics · Physics 2019-10-02 Bikash Kanungo , Vikram Gavini

We present a systematic numerical iteration approach to study the evolution properties of the spin-boson systems, which works well in whole coupling regime. This approach involves the evaluation of a set of coefficients for the formal…

Quantum Physics · Physics 2018-12-11 Xueying Liu , Xuezao Ren , Chen Wang , Gao Xianlong , Kelin Wang

We present an adaptive grid matrix-free operator approximation scheme based on a "product-convolution" interpolation of convolution operators. This scheme is appropriate for operators that are locally translation-invariant, even if these…

Numerical Analysis · Mathematics 2019-02-07 Nick Alger , Vishwas Rao , Aaron Myers , Tan Bui-Thanh , Omar Ghattas

We consider the task of simulating time evolution under a Hamiltonian $H$ within its low-energy subspace. Assuming access to a block-encoding of $H'=(H-E)/\lambda$ for some $E \in \mathbb R$, the goal is to implement an…

Quantum Physics · Physics 2024-08-28 Alexander Zlokapa , Rolando D. Somma

We present a quantum algorithm for the dynamical simulation of time-dependent Hamiltonians. Our method involves expanding the interaction-picture Hamiltonian as a sum of generalized permutations, which leads to an integral-free Dyson series…

Quantum Physics · Physics 2021-09-15 Yi-Hsiang Chen , Amir Kalev , Itay Hen

In this work, we make use of Lie algebraic methods to obtain the time evolution operator for an optomechanical system with linear and quadratic couplings between the field and the mechanical oscillator. Firstly, we consider the case of a…

Quantum Physics · Physics 2025-04-25 Luis A. Medina-Dozal , Alejandro R. Urzúa , José Récamier-Angelini

We propose a scheme to deal with certain time-dependent non-Hermitian Hamiltonian operators $H(t)$ that generate a real phase in their time-evolution. This involves the use of invariant operators $I_{PH}(t)$ that are pseudo-Hermitian with…

Quantum Physics · Physics 2017-06-19 Boubakeur Khantoul , A. Bounames , M. Maamache

Hamiltonian simulation is a central task in quantum computing, with wide-ranging applications in quantum chemistry, condensed matter physics, and combinatorial optimization. A fundamental challenge lies in approximating the unitary…

Quantum Physics · Physics 2025-05-15 Molena Nguyen , Naihuan Jing

We propose a numerical method for approximate calculations of the time evolution of point particle systems given only the system's Hamiltonian function and initial conditions. The method both generates and solves the equations of motion…

Computational Physics · Physics 2022-12-27 José M. L. Amoreira , Luís J. M. Amoreira

We propose a new method for simulating certain type of time-dependent Hamiltonian $H(t) = \sum_{i=1}^m \gamma_i(t) H_i$ where $\gamma_i(t)$ (and its higher order derivatives) is bounded, computable function of time $t$, and each $H_i$ is…

Quantum Physics · Physics 2024-10-21 Nhat A. Nghiem

We present an efficient quantum algorithm for simulating the evolution of a sparse Hamiltonian H for a given time t in terms of a procedure for computing the matrix entries of H. In particular, when H acts on n qubits, has at most a…

Quantum Physics · Physics 2007-05-23 Dominic W. Berry , Graeme Ahokas , Richard Cleve , Barry C. Sanders

We consider the problem of learning the evolution operator for the time-dependent Schr\"{o}dinger equation, where the Hamiltonian may vary with time. Existing neural network-based surrogates often ignore fundamental properties of the…

Machine Learning · Statistics 2026-04-07 Yash Patel , Unique Subedi , Ambuj Tewari

In quantum mechanics the time operator $\Theta$ satisfies the commutation relation $[\Theta,H]=i$, and thus it may be thought of as being canonically conjugate to the Hamiltonian $H$. The time operator associated with a given Hamiltonian…

High Energy Physics - Theory · Physics 2015-06-03 Carl M. Bender , M. Gianfreda

Given a quantum Hamiltonian and its evolution time, the corresponding unitary evolution operator can be constructed in many different ways, corresponding to different trajectories between the desired end-points and different series…

Quantum Physics · Physics 2017-03-14 Apoorva Patel , Anjani Priyadarsini