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Conventional diagonalization methods to calculate nuclear energy levels in the framework of the configuration-interaction (CI) shell model approach are prohibited in very large model spaces. The shell model Monte Carlo (SMMC) is a powerful…

Nuclear Theory · Physics 2025-01-08 Y. Alhassid , M. Bonett-Matiz , C. N. Gilbreth , S. Vartak

We study a two-component mixture of fermionic dipoles in two dimensions at zero temperature, interacting via a purely repulsive $1/r^3$ potential. This model can be realized with ultracold atoms or molecules, when their dipole moments are…

We address the calculation of dynamical correlation functions for many fermion systems at zero temperature, using the auxiliary-field quantum Monte Carlo method. The two-dimensional Hubbard hamiltonian is used as a model system. Although…

Strongly Correlated Electrons · Physics 2016-08-24 Ettore Vitali , Hao Shi , Mingpu Qin , Shiwei Zhang

Confined quantum systems involving $N$ identical interacting fermions are found in many areas of physics, including condensed matter, atomic, nuclear and chemical physics. In a previous series of papers, a manybody perturbation method that…

Quantum Physics · Physics 2015-06-18 D. K. Watson

The pairing properties of ultracold fermions, with an attractive interaction, loaded in a honeycomb (graphene-like) optical lattice are studied in a mean-field approach. We emphasize, in the presence of a harmonic trap, the unambiguous…

Quantum Gases · Physics 2015-06-03 Benoît Grémaud

We study spin-1/2 fermions, interacting via a two-body contact potential, in a one-dimensional harmonic trap. Applying exact diagonalization, we investigate their behavior at finite interaction strength, and discuss the role of the…

Quantum Physics · Physics 2013-09-09 Tomasz Sowiński , Tobias Grass , Omjyoti Dutta , Maciej Lewenstein

We introduce a generic and accessible implementation of an exact diagonalization method for studying few-fermion models. Our aim is to provide a testbed for the newcomers to the field as well as a stepping stone for trying out novel…

Quantum Gases · Physics 2023-05-01 Lukas Rammelmüller , David Huber , Artem G. Volosniev

A grand canonical system of non-interacting fermions on a square lattice is considered at zero temperature. Three different phases exist: an empty lattice, a completely filled lattice and a liquid phase which interpolates between the other…

Condensed Matter · Physics 2015-06-25 M. Hettler , K. Ziegler

The ground-state properties of a few spin-1/2 fermions with different masses and interacting via short-range contact forces are studied within an exact diagonalization approach. It is shown that, depending on the shape of the external…

Quantum Gases · Physics 2016-10-21 Daniel Pęcak , Tomasz Sowiński

The behavior of ultracold atomic gases depends crucially on the two-body scattering properties of these systems. We develop a multichannel scattering theory for atom-atom collisions in quasi-one-dimensional (quasi-1D) geometries such as…

Condensed Matter · Physics 2009-11-10 Brian E. Granger , D. Blume

We demonstrate the feasibility of realistic Shell-Model Monte Carlo (SMMC) calculations spanning multiple major shells, using a realistic interaction whose bad saturation and shell properties have been corrected by a newly developed general…

Nuclear Theory · Physics 2009-10-30 D. J. Dean , M. T. Ressell , M. Hjorth-Jensen , S. E. Koonin , K. Langanke , A. P. Zuker

A shell model study of the low energy region of the spectra in Ge isotopes for $38\leq N\leq 50$ is presented, analyzing the excitation energies, quadrupole moments, $B(E2)$ values and occupation numbers. The theoretical results have been…

Nuclear Theory · Physics 2012-09-27 J. G. Hirsch , P. C. Srivastava

We present an exact Quantum Monte Carlo study of the attractive 1-dimensional Hubbard model with imbalanced fermion population. The pair-pair correlation function, which decays monotonically in the absence of polarization P, develops…

Strongly Correlated Electrons · Physics 2009-11-13 G. G. Batrouni , M. H. Huntley , V. G. Rousseau , R. T. Scalettar

We propose a simple bose-fermi model in two dimensions, with a coupling that converts pairs of opposite spin fermions into localized bosons and vice versa. We show that tracing out one of the degrees, either the bosons or fermions,…

Superconductivity · Physics 2020-10-23 Maciej M. Maśka , Nandini Trivedi

In this work we present a novel quantum Monte-Carlo method for fermions, based on an exact decomposition of the Boltzmann operator $exp(-\beta H)$. It can be seen as a synthesis of several related methods. It has the advantage that it is…

Strongly Correlated Electrons · Physics 2009-10-31 S. Rombouts , K. Heyde , N. Jachowicz

We construct valence-space Hamiltonians for use in shell-model calculations, where the residual two-body interaction is based on symmetry principles and the low-momentum expansion from chiral effective field theory. In addition to the usual…

Nuclear Theory · Physics 2018-11-13 Lukas Huth , Victoria Durant , Johannes Simonis , Achim Schwenk

We present a new lattice Monte Carlo approach developed for studying large numbers of strongly interacting nonrelativistic fermions, and apply it to a dilute gas of unitary fermions confined to a harmonic trap. Our lattice action is highly…

High Energy Physics - Lattice · Physics 2011-11-04 Michael G. Endres , David B. Kaplan , Jong-Wan Lee , Amy N. Nicholson

We probe the superconducting gap in the zero temperature ground state of an attractively interacting spin-imbalanced two-dimensional Fermi gas with Diffusion Monte Carlo. A condensate fraction at nonzero pair momentum evidences a spatially…

Strongly Correlated Electrons · Physics 2019-12-11 D. C. W. Foo , G. J. Conduit

Ultracold atomic gases with short-range interactions are characterized by a number of universal species-independent relations. Many of these relations involve the two-body Tan contact. Employing the canonical ensemble, we determine the Tan…

Quantum Gases · Physics 2015-06-16 Yangqian Yan , D. Blume

Among many types of quantum entanglement properties, the entanglement spectrum provides more abundant information than other observables. Exact diagonalization and density matrix renormalization group method could handle the system in…

Strongly Correlated Electrons · Physics 2025-03-05 Weilun Jiang , Xiaofan Luo , Bin-Bin Mao , Zheng Yan