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We study spin-1/2 fermions in spin dependent potentials under the \emph{spin model approximation}, in which interatomic collisions that change the total occupation of single-particle modes are ignored. The spin model approximation maps the…

Quantum Gases · Physics 2020-09-02 Michael L. Wall

We study analytically the corrections to the leading terms in the Renyi entropy of a massive lattice theory, showing significant deviations from naive expectations. In particular, we show that finite size and finite mass effects give rise…

High Energy Physics - Theory · Physics 2012-05-31 Elisa Ercolessi , Stefano Evangelisti , Fabio Franchini , Francesco Ravanini

We investigate a generalized antiferromagnetic cluster XY model in a transverse magnetic field, where long-range interactions decay algebraically with distance. This model can be exactly solvable within a free fermion framework. By…

Strongly Correlated Electrons · Physics 2025-02-07 Tian-Cheng Yi , Chengxiang Ding , Maoxin Liu , Liangsheng Li , Wen-Long You

Conformal field theories in curved backgrounds have been used to describe inhomogeneous one-dimensional systems, such as quantum gases in trapping potentials and non-equilibrium spin chains. This approach provided, in a elegant and simple…

Statistical Mechanics · Physics 2019-03-26 Sara Murciano , Paola Ruggiero , Pasquale Calabrese

The $S=1/2$, nearest-neighbor, quantum Heisenberg antiferromagnet on the square lattice with spatially anisotropic couplings is reconsidered, with particular attention to the following question: at T=0, does N\'eel orderdevelop at…

Condensed Matter · Physics 2011-01-06 Ian Affleck , Martin P. Gelfand , Rajiv R. P. Singh

We consider a spin-$\frac{1}{2}$ chain with competing nearest and next-nearest neighbor interactions within a transverse magnetic field, which is known to be an equiavelent to the ANNNI model. When studing thermodynamics of the 2D ANNNI…

Condensed Matter · Physics 2009-10-28 H. Rieger , G. Uimin

The subject matter of this work is a 1D quantum spin - $\frac{1}{2}$ chain associated with the inhomogeneous six-vertex model possessing an additional ${\cal Z}_r$ symmetry. The model is studied in a certain parametric domain, where it is…

High Energy Physics - Theory · Physics 2023-07-19 Gleb A. Kotousov , Sergei L. Lukyanov

We present exact formulas for the entanglement and R\'{e}nyi entropies generated at a quantum point contact (QPC) in terms of the statistics of charge fluctuations, which we illustrate with examples from both equilibrium and non-equilibrium…

Mesoscale and Nanoscale Physics · Physics 2011-05-04 H. Francis Song , Christian Flindt , Stephan Rachel , Israel Klich , Karyn Le Hur

We use the Density-Matrix Renormalization Group to study the single-particle and two-particle correlation functions of spinless fermions in the ground state of a quarter-filled ladder. This ladder consists of two chains having an in-chain…

Strongly Correlated Electrons · Physics 2009-11-07 L. G. Caron , C. Bourbonnais

We study the scaling properties of the entanglement entropy (EE) near quantum critical points in interacting random antiferromagnetic (AF) spin chains. Using density-matrix renormalization group, we compute the half-chain EE near the…

Disordered Systems and Neural Networks · Physics 2024-03-05 Prashant Kumar , R. N. Bhatt

The reduced density matrix of many-body systems possessing an additive conserved quantity can be decomposed in orthogonal sectors which can be independently analyzed. Recently, these have been proven to equally contribute to entanglement…

Statistical Mechanics · Physics 2020-08-05 Xhek Turkeshi , Paola Ruggiero , Vincenzo Alba , Pasquale Calabrese

Using a Corner Transfer Matrix approach, we compute the bipartite entanglement R\'enyi entropy in the off-critical perturbations of non-unitary conformal minimal models realised by lattice spin chains Hamiltonians related to the Forrester…

High Energy Physics - Theory · Physics 2016-07-18 Davide Bianchini , Francesco Ravanini

Using equivalencies between different models we reduce the model of two spin-1/2 Heisenberg chains crossed at one point to the model of free fermions. The spin-spin correlation function is calculated by summing the perturbation series in…

Strongly Correlated Electrons · Physics 2009-11-11 S. A. Reyes , A. M. Tsvelik

We study the spectrum of fermions hopping on a chain with a weak incommensuration close to dimerization; both q, the deviation of the wave number from pi, and delta, the strength of the incommensuration, are small. For free fermions, we use…

Strongly Correlated Electrons · Physics 2009-10-31 Diptiman Sen , Siddhartha Lal

In this paper, we investigate the ground-state entanglement entropy in inhomogeneous free-boson models in one spatial dimension. We develop a powerful method to extract the leading term in the entanglement scaling, based on the analytic…

Statistical Mechanics · Physics 2025-08-07 Pierre-Antoine Bernard , Rafael I. Nepomechie , Gilles Parez , Eric Ragoucy , David Raveh , Luc Vinet

We study the entanglement properties of non-Hermitian free fermionic models with translation symmetry using the correlation matrix technique. Our results show that the entanglement entropy has a logarithmic correction to the area law in…

Mesoscale and Nanoscale Physics · Physics 2021-09-22 Yi-Bin Guo , Yi-Cong Yu , Rui-Zhen Huang , Li-Ping Yang , Run-Ze Chi , Hai-Jun Liao , Tao Xiang

Dynamic autocorrelations $<S_i^{\alpha}(t) S_i^{\alpha}>$ (\alpha=x,z) of an isolated impurity spin in a S=1/2 XX chain are calculated. The impurity spin, defined by a local change in the nearest-neighbor coupling, is either in the bulk or…

Statistical Mechanics · Physics 2009-10-31 Joachim Stolze , Michael Vogel

We present a simple construction for a tridiagonal matrix $T$ that commutes with the hopping matrix for the entanglement Hamiltonian ${\cal H}$ of open finite free-Fermion chains associated with families of discrete orthogonal polynomials.…

Statistical Mechanics · Physics 2019-10-03 Nicolas Crampé , Rafael I. Nepomechie , Luc Vinet

We construct a finite spin-1/2 chain model (quantum domino) interacting with a Fermi field, capable of emitting a scalar fermion from the last spin in the chain. The chain with dynamics gradually reversing the neighbouring spins emits…

Mathematical Physics · Physics 2012-12-11 Pavel Bóna , Michal Širaň

We study equilibrium density and spin density profiles for a model of cold one-dimensional spin 1/2 fermions interacting via inverse square interaction and exchange in an external harmonic trap. This model is the well-known spin-Calogero…

Quantum Gases · Physics 2011-02-01 M. Kulkarni , A. G. Abanov