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Classical nonlinear theories are highly successful in describing far-from-equilibrium dynamics of magnets, encompassing phenomena such as parametric resonance, ultrafast switching, and even chaos. However, at ultrashort length and time…

Mesoscale and Nanoscale Physics · Physics 2025-12-15 Lukas Körber , Pim Coenders , Johan H. Mentink

We introduce a non perturbative general approximation scheme (NGAS) that can handle interactions of any strength in quantum theory. This approach starts with an input Hamiltonian that can be solved exactly. The interaction effects are then…

Quantum Physics · Physics 2025-10-09 B. P. Mahapatra

In past decades the scientific community has been looking for a reliable first-principles method to predict the electronic structure of solids with high accuracy. Here we present an approach which we call the quasiparticle self-consistent…

Materials Science · Physics 2009-11-11 M. van Schilfgaarde , T. Kotani , S. Faleev

We propose SnCQA, a set of hardware-efficient variational circuits of equivariant quantum convolutional circuits respective to permutation symmetries and spatial lattice symmetries with the number of qubits $n$. By exploiting permutation…

We develop a finite-temperature perturbation theory for quasi-one-dimensional quantum spin systems, in the manner suggested by H.J. Schulz (1996) and use this formalism to study their dynamical response. The corrections to the random-phase…

Strongly Correlated Electrons · Physics 2009-11-07 Marc Bocquet

VQA have attracted a lot of attention from the quantum computing community for the last few years. Their hybrid quantum-classical nature with relatively shallow quantum circuits makes them a promising platform for demonstrating the…

The classical XXZ triangular-lattice antiferromagnet (TAF) shows both an Ising and a BKT transition, related to the chirality and the in-plane spin components, respectively. In this paper the quantum effects on the thermodynamic quantities…

Statistical Mechanics · Physics 2009-10-31 L. Capriotti , A. Cuccoli , V. Tognetti , P. Verrucchi , R. Vaia

Hybrid quantum mechanical-molecular mechanical (QM/MM) simulations are widely used in enzyme simulation. Over ten convergence studies of QM/MM methods have revealed over the past several years that key energetic and structural properties…

Chemical Physics · Physics 2017-01-11 Maria Karelina , Heather J. Kulik

The quantum spin Hall effect (QSHE) has formed the seed for contemporary research on topological quantum states of matter. Since its discovery in HgTe/CdTe quantum wells and AlGaAs/GaAs heterostructures, all such systems have so far been…

Strongly Correlated Electrons · Physics 2018-11-07 Gang Li , Werner Hanke , Ewelina M. Hankiewicz , Felix Reis , Joerg Schaefer , Ralph Claessen , Congjun Wu , Ronny Thomale

In this work we extend the results of [1] where, Semiclassical Selfconsistent Configurations (SSC) formalism was introduced. The scheme combines quantum field theory on a background space-time, semiclassical treatment of gravitation and…

General Relativity and Quantum Cosmology · Physics 2018-11-13 Pedro Cañate , Erandy Ramirez , Daniel Sudarsky

Atomistic spin dynamics (ASD) is a standard tool to model the magnetization dynamics of a variety of materials. The fundamental dynamical model underlying ASD is entirely classical. In this paper, we present two approaches to effectively…

Materials Science · Physics 2024-07-01 Marco Berritta , Stefano Scali , Federico Cerisola , Janet Anders

A quasi-static approximation (QSA) for modified gravity can be applied in a number of ways. We consider three different analytical formulations based on applying this approximation to: (1) the field equations; (2) the equations for the two…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-03 Francesco Pace , Richard Battye , Emilio Bellini , Lucas Lombriser , Filippo Vernizzi , Boris Bolliet

The proliferation of quantum fluctuations and long-range entanglement presents an outstanding challenge for the numerical simulation of interacting spin systems with exotic ground states. Here, we present a toolset of Chebyshev…

Strongly Correlated Electrons · Physics 2024-02-28 Francisco M. O. Brito , Aires Ferreira

In this paper, we introduce stochastic simulated quantum annealing (SSQA) for large-scale combinatorial optimization problems. SSQA is designed based on stochastic computing and quantum Monte Carlo, which can simulate quantum annealing (QA)…

Quantum Physics · Physics 2024-07-25 Naoya Onizawa , Ryoma Sasaki , Duckgyu Shin , Warren J. Gross , Takahiro Hanyu

Simulating the unitary dynamics of a quantum system is a fundamental problem of quantum mechanics, in which quantum computers are believed to have significant advantage over their classical counterparts. One prominent such instance is the…

Quantum Physics · Physics 2024-09-04 John M. Martyn , Yuan Liu , Zachary E. Chin , Isaac L. Chuang

The main ideas and some of the most important results of the spherically symmetric self-consistent approach and a number of related theoretical algorithms are presented. These methods make it possible to study low-dimensional…

Strongly Correlated Electrons · Physics 2026-05-18 A. F. Barabanov , V. E. Valiulin , A. V. Mikheyenkov , P. S. Savchenkov

In this letter, I develop a new topologically invariant coherent state path integral for spin systems, and apply it to the quantum Heisenberg model on a square lattice. As a result, the quantum nonlinear $\sigma$ model for arbitrary values…

Strongly Correlated Electrons · Physics 2007-05-23 Wei-Min Zhang

We provide a quantization of the Schwarzschild spacetime in the presence of a cosmological constant, based on midisuperspace methods developed in the spherically symmetric sector of loop quantum gravity, using in particular the 'improved…

General Relativity and Quantum Cosmology · Physics 2025-03-11 Esteban Mato , Javier Olmedo , Sahil Saini

The application of average Hamiltonian theory (AHT) to magnetic resonance and quantum sensing informs pulse sequence design, for example, by providing efficient approximations of spin dynamics while retaining important physical…

Following on from our recent work, we investigate a stochastic approach to non-equilibrium quantum spin systems. We show how the method can be applied to a variety of physical observables and for different initial conditions. We provide…

Statistical Mechanics · Physics 2020-01-24 S. De Nicola , B. Doyon , M. J. Bhaseen