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In 2011, the fundamental gap conjecture for Schr\"odinger operators was proven. This can be used to estimate the ground state energy of the time-independent Schr\"odinger equation with a convex potential and relative error \epsilon.…

Quantum Physics · Physics 2013-09-26 Anargyros Papageorgiou , Iasonas Petras

The Quantum Singular Value Transformation (QSVT) is a technique that provides a unified framework for describing many of the quantum algorithms discovered to date. We implement a noise-free simulation of the technique to investigate how it…

Quantum Physics · Physics 2023-07-26 Alexis Ralli , Gabriel Greene-Diniz , David Muñoz Ramo , Nathan Fitzpatrick

One of the central challenges in the study of quantum many-body systems is the complexity of simulating them on a classical computer. A recent advance of Landau et al. gave a polynomial time algorithm to actually compute a succinct…

Quantum Physics · Physics 2017-09-13 Itai Arad , Zeph Landau , Umesh Vazirani , Thomas Vidick

The energy minimization involved in density functional calculations of electronic systems can be carried out using an exponential transformation that preserves the orthonormality of the orbitals. The energy of the system is then represented…

Computational Physics · Physics 2022-11-09 Aleksei V. Ivanov , Elvar Ö. Jónsson , Tejs Vegge , Hannes Jónsson

We provide faster algorithms and improved sample complexities for approximating the top eigenvector of a matrix. Offline Setting: Given an $n \times d$ matrix $A$, we show how to compute an $\epsilon$ approximate top eigenvector in time…

Data Structures and Algorithms · Computer Science 2016-05-31 Chi Jin , Sham M. Kakade , Cameron Musco , Praneeth Netrapalli , Aaron Sidford

We develop a formalism to calculate the quasi-particle energy within the GW many-body perturbation correction to the density functional theory (DFT). The occupied and virtual orbitals of the Kohn-Sham (KS) Hamiltonian are replaced by…

Mesoscale and Nanoscale Physics · Physics 2015-06-18 Daniel Neuhauser , Yi Gao , Christopher Arntsen , Cyrus Karshenas , Eran Rabani , Roi Baer

Simulating a quantum system is more efficient on a quantum computer than on a classical computer. The time required for solving the Schr\"odinger equation to obtain molecular energies has been demonstrated to scale polynomially with system…

Quantum Physics · Physics 2019-03-27 Hefeng Wang , Sabre Kais , Alán Aspuru-Guzik , Mark R. Hoffmann

For compact self-adjoint operators in Hilbert spaces, two algorithms are proposed to provide fully computable a posteriori error estimate for eigenfunction approximation. Both algorithms apply well to the case of tight clusters and multiple…

Numerical Analysis · Mathematics 2022-07-19 Xuefeng Liu , Tomáš Vejchodský

Including finite-temperature effects from the electronic degrees of freedom in electronic structure calculations of semiconductors and metals is desired; however, in practice it remains exceedingly difficult when using zero-temperature…

Chemical Physics · Physics 2016-11-24 Alicia Rae Welden , Alexander A. Rusakov , Dominika Zgid

We present a new generic approach to the condensed-matter ground-state problem which is complementary to variational techniques and works directly in the thermodynamic limit. Relaxing the ground-state problem, we obtain semidefinite…

Strongly Correlated Electrons · Physics 2012-08-08 Thomas Barthel , Robert Hübener

Iterative Green's function, based on cyclic reduction of block tridiagonal matrices, has been the ideal algorithm, through tight-binding models, to compute the surface density-of-states of semi-infinite topological electronic materials. In…

Strongly Correlated Electrons · Physics 2021-09-22 Yi-Xin Sha , Bo-Yuan Liu , Hao-Zhe Gao , Heng-Bin Cheng , Hai-Li Zhang , Ming-Yao Xia , Steven G. Johnson , Ling Lu

Accurate computation of multiple eigenvalues of quantum Hamiltonians is essential in quantum chemistry, materials science, and molecular spectroscopy. Estimating excited-state energies is challenging for classical algorithms due to…

Quantum Physics · Physics 2026-05-22 Grzegorz Rajchel-Mieldzioć , Szymon Pliś , Emil Zak

Under suitable assumptions, the quantum phase estimation (QPE) algorithm is able to achieve Heisenberg-limited precision scaling in estimating the ground state energy. However, QPE requires a large number of ancilla qubits and large circuit…

Quantum Physics · Physics 2022-02-04 Lin Lin , Yu Tong

Key properties of physical systems can be described by the eigenvalues of matrices that represent the system. Computational algorithms that determine the eigenvalues of these matrices exist, but they generally suffer from a loss of…

Quantum Physics · Physics 2023-10-31 T. Powers , R. M. Rajapakse

We present a quantum-classical hybrid implementation of the Liouvillian recursion method to compute many-body Green's functions using a quantum computer. From an approximate ground state preparation circuit, this algorithm produces the…

Novel results for the self-consistent single-particle spectral function and self-energy are presented for non-degenerate one-component Coulomb systems at various densities and temperatures. The GW^0-method for the dynamical self-energy is…

Plasma Physics · Physics 2009-11-13 Carsten Fortmann

The application of numerical techniques to the study of energy landscapes of large systems relies on sufficient sampling of the stationary points. Since the number of stationary points is believed to grow exponentially with system size, we…

Statistical Mechanics · Physics 2014-12-11 Dhagash Mehta , Ciaran Hughes , Michael Kastner , David J Wales

We describe an efficient approximation algorithm for evaluating the ground-state energy of the classical Ising Hamiltonian with linear terms on an arbitrary planar graph. The running time of the algorithm grows linearly with the number of…

Quantum Physics · Physics 2009-09-16 Nikhil Bansal , Sergey Bravyi , Barbara M. Terhal

In this work we provide a new direct and non-numerical technique to obtain the surface Green's functions for three-dimensional systems. This technique is based on the ideas presented in Phys. Rev. B 100, 081106(R), in which we start with an…

Mesoscale and Nanoscale Physics · Physics 2020-03-11 Sarah Pinon , Vardan Kaladzhyan , Cristina Bena

The self-healing diffusion Monte Carlo algorithm (SHDMC) [Phys. Rev. B {\bf 79}, 195117 (2009), {\it ibid.} {\bf 80}, 125110 (2009)] is shown to be an accurate and robust method for calculating the ground state of atoms and molecules. By…

Strongly Correlated Electrons · Physics 2015-05-14 Michal Bajdich , Murilo L. Tiago , Randolph Q. Hood , Paul R. C. Kent , Fernando A. Reboredo
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