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We introduce an analytical iterative method, the density matrix recursion method, to generate arbitrary reduced density matrices of superpositions of short-range dimer coverings on periodic or non-periodic quantum spin-1/2 ladder lattices,…

Quantum Physics · Physics 2013-01-22 Himadri Shekhar Dhar , Aditi Sen De , Ujjwal Sen

A new algorithm to compute the restricted singular value decomposition of dense matrices is presented. Like Zha's method \cite{Zha92}, the new algorithm uses an implicit Kogbetliantz iteration, but with four major innovations. The first…

Numerical Analysis · Mathematics 2020-02-13 Ian N. Zwaan

We develop a Liouville perturbation theory for weakly driven and weakly open quantum systems in situations when the unperturbed system has a number of conservations laws. If the perturbation violates the conservation laws, it drives the…

Strongly Correlated Electrons · Physics 2018-01-24 Zala Lenarčič , Florian Lange , Achim Rosch

In [Phys. Rev. Lett. 127, 023001 (2021)] a reduced density matrix functional theory (RDMFT) has been proposed for calculating energies of selected eigenstates of interacting many-fermion systems. Here, we develop a solid foundation for this…

Quantum Physics · Physics 2022-05-06 Julia Liebert , Federico Castillo , Jean-Philippe Labbé , Christian Schilling

Many quantum algorithms, including recently proposed hybrid classical/quantum algorithms, make use of restricted tomography of the quantum state that measures the reduced density matrices, or marginals, of the full state. The most…

Quantum Physics · Physics 2018-05-16 Nicholas C. Rubin , Ryan Babbush , Jarrod McClean

We propose an energy-driven stochastic master equation for the density matrix as a dynamical model for quantum state reduction. In contrast, most previous studies of state reduction have considered stochastic extensions of the Schr\"odinger…

Quantum Physics · Physics 2016-12-30 Dorje C. Brody , Lane P. Hughston

We clarify different definitions of the density matrix by proposing the use of different names, the full density matrix for a single-closed quantum system, the compressed density matrix for the averaged single molecule state from an…

Quantum Physics · Physics 2007-05-23 Gui Lu Long , Yi-Fan Zhou , Jia-Qi Jin , Yang Sun , Hai-Woong Lee

We present a real-space method for computing the random phase approximation (RPA) correlation energy within Kohn-Sham density functional theory, leveraging the low-rank nature of the frequency-dependent density response operator. In…

Computational Physics · Physics 2025-04-03 Boqin Zhang , Shikhar Shah , John E. Pask , Edmond Chow , Phanish Suryanarayana

The possibility to simulate the properties of many-body open quantum systems with a large number of degrees of freedom is the premise to the solution of several outstanding problems in quantum science and quantum information. The challenge…

Quantum Physics · Physics 2019-07-03 Alexandra Nagy , Vincenzo Savona

Variational methods are highly valuable computational tools for solving high-dimensional quantum systems. In this paper, we explore the effectiveness of three variational methods: the density matrix renormalization group (DMRG), Boltzmann…

Quantum Physics · Physics 2024-04-18 Daming Li

We present a real-space spectral method for computing the orbital magnetization of crystals. Starting from the commutator form of the orbital magnetization operator, we formulate an energy-resolved spectral function that is amenable to…

We propose a method based on the Wang-Landau algorithm to numerically generate the spectral densities of random matrix ensembles. The method employs Dyson's log-gas formalism for random matrix eigenvalues and also enables one to…

Statistical Mechanics · Physics 2013-01-28 Santosh Kumar

We use the homological perturbation lemma to produce explicit formulas computing the class in the twisted de Rham complex represented by an arbitrary polynomial. This is a non-asymptotic version of the method of Feynman diagrams. In…

Mathematical Physics · Physics 2019-11-05 Theo Johnson-Freyd

In this work, we present a method to exponentiate non-sparse indefinite low-rank matrices on a quantum computer. Given an operation for accessing the elements of the matrix, our method allows singular values and associated singular vectors…

Quantum Physics · Physics 2018-01-31 Patrick Rebentrost , Adrian Steffens , Seth Lloyd

In modern cosmology, scalar fields with screening mechanisms are often used as explanations for phenomena like dark energy or dark matter. Amongst a zoo of models, the environment dependent dilaton, screened by the Polyakov-Damour…

High Energy Physics - Phenomenology · Physics 2023-09-01 Christian Käding , Mario Pitschmann , Caroline Voith

This paper reviews the linearized path integral approach for computing time dependent properties of systems that can be approximated using a mixed quantum-classical description. This approach is applied to studying vibrational pure…

Chemical Physics · Physics 2009-11-13 Z. Ma , D. F. Coker

A nonperturbative electron transfer rate theory is developed based on the reduced density matrix dynamics, which can be evaluated readily for the Debye solvent model without further approximation. Not only does it recover for reaction rates…

Quantum Physics · Physics 2007-05-23 Ping Han , Rui-Xue Xu , Baiqing Li , Jian Xu , Ping Cui , Yan Mo , YiJing Yan

Quantum embedding methods enable the study of large, strongly correlated quantum systems by (usually self-consistent) decomposition into computationally manageable subproblems, in the spirit of divide-and-conquer methods. Among these,…

Strongly Correlated Electrons · Physics 2025-03-14 Alicia Negre , Fabian Faulstich , Raehyun Kim , Thomas Ayral , Lin Lin , Eric Cancès

A precise understanding of the influence of a quantum system's environment on its dynamics, which is at the heart of the theory of open quantum systems, is crucial for further progress in the development of controllable large-scale quantum…

Quantum Physics · Physics 2022-10-10 I. A. Luchnikov , E. O. Kiktenko , M. A. Gavreev , H. Ouerdane , S. N. Filippov , A. K. Fedorov

We present in this report 1+1 dimensional nonlinear partial differential equation integrable through inverse scattering transform. The integrable system under consideration is a pseudo-Hermitian reduction of a matrix generalization of…

Exactly Solvable and Integrable Systems · Physics 2018-02-13 T. I. Valchev , A. B. Yanovski
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