scholarly journals Complete spectrum of quantum integrable lattice models associated to Y(gl(n)) by separation of variables

2019 ◽  
Vol 6 (6) ◽  
Author(s):  
Jean Michel Maillet ◽  
Giuliano Niccoli
Keyword(s):  
Transfer Matrix ◽  
Separation Of Variables ◽  
Lattice Models ◽  
Complete Characterization ◽  
Simple Spectrum ◽  
Transfer Matrices ◽  
Integrable Lattice ◽  
Transfer Matrix Spectrum ◽  
Integrable Lattice Models ◽  
Matrix Spectrum

We apply our new approach of quantum Separation of Variables (SoV) to the complete characterization of the transfer matrix spectrum of quantum integrable lattice models associated to \bm{gl_n}𝐠𝐥𝐧-invariant \bm{R}𝐑-matrices in the fundamental representations. We consider lattices with \bm{N}𝐍-sites and general quasi-periodic boundary conditions associated to an arbitrary twist matrix \bm{K}𝐊 having simple spectrum (but not necessarily diagonalizable). In our approach the SoV basis is constructed in an universal manner starting from the direct use of the conserved charges of the models, e.g. from the commuting family of transfer matrices. Using the integrable structure of the models, incarnated in the hierarchy of transfer matrices fusion relations, we prove that our SoV basis indeed separates the spectrum of the corresponding transfer matrices. Moreover, the combined use of the fusion rules, of the known analytic properties of the transfer matrices and of the SoV basis allows us to obtain the complete characterization of the transfer matrix spectrum and to prove its simplicity. Any transfer matrix eigenvalue is completely characterized as a solution of a so-called quantum spectral curve equation that we obtain as a difference functional equation of order \bm{n}𝐧. Namely, any eigenvalue satisfies this equation and any solution of this equation having prescribed properties that we give leads to an eigenvalue. We construct the associated eigenvector, unique up to normalization, of the transfer matrices by computing its decomposition on the SoV basis that is of a factorized form written in terms of the powers of the corresponding eigenvalues. Finally, if the twist matrix \bm{K}𝐊 is diagonalizable with simple spectrum we prove that the transfer matrix is also diagonalizable with simple spectrum. In that case, we give a construction of the Baxter \bm{Q}𝐐-operator and show that it satisfies a \bm{T}𝐓-\bm{Q}𝐐 equation of order \bm{n}𝐧, the quantum spectral curve equation, involving the hierarchy of the fused transfer matrices.

scholarly journals On quantum separation of variables beyond fundamental representations

2021 ◽  
Vol 10 (2) ◽  
Author(s):  
Jean Michel Maillet ◽  
Giuliano Niccoli
Keyword(s):  
Functional Equation ◽  
Transfer Matrix ◽  
Separation Of Variables ◽  
Operator Family ◽  
Transfer Matrices ◽  
Conserved Charges ◽  
Transfer Matrix Spectrum ◽  
Lax Operator ◽  
The One ◽  
Matrix Spectrum

We describe the extension, beyond fundamental representations of the Yang-Baxter algebra, of our new construction of separation of variables bases for quantum integrable lattice models. The key idea underlying our approach is to use the commuting conserved charges of the quantum integrable models to generate bases in which their spectral problem is separated, i.e. in which the wave functions are factorized in terms of specific solutions of a functional equation. For the so-called “non-fundamental” models we construct two different types of SoV bases. The first is given from the fundamental quantum Lax operator having isomorphic auxiliary and quantum spaces and that can be obtained by fusion of the original quantum Lax operator. The construction essentially follows the one we used previously for fundamental models and allows us to derive the simplicity and diagonalizability of the transfer matrix spectrum. Then, starting from the original quantum Lax operator and using the full tower of the fused transfer matrices, we introduce a second type of SoV bases for which the proof of the separation of the transfer matrix spectrum is naturally derived. We show that, under some special choice, this second type of SoV bases coincides with the one associated to Sklyanin’s approach. Moreover, we derive the finite difference type (quantum spectral curve) functional equation and the set of its solutions defining the complete transfer matrix spectrum. This is explicitly implemented for the integrable quantum models associated to the higher spin representations of the general quasi-periodic Y(gl_{2})Y(gl2) Yang-Baxter algebra. Our SoV approach also leads to the construction of a QQ-operator in terms of the fused transfer matrices. Finally, we show that the QQ-operator family can be equivalently used as the family of commuting conserved charges enabling to construct our SoV bases.

scholarly journals On scalar products in higher rank quantum separation of variables

2020 ◽  
Vol 9 (6) ◽  
Author(s):  
Jean Michel Maillet ◽  
Giuliano Niccoli ◽  
Louis Vignoli
Keyword(s):  
Transfer Matrix ◽  
Separation Of Variables ◽  
Lattice Models ◽  
Simple Spectrum ◽  
Conserved Charges ◽  
Integrable Lattice ◽  
Rank One ◽  
Higher Rank ◽  
Left And Right ◽  
Scalar Products

Using the framework of the quantum separation of variables (SoV) for higher rank quantum integrable lattice models , we introduce some foundations to go beyond the obtained complete transfer matrix spectrum description, and open the way to the computation of matrix elements of local operators. This first amounts to obtain simple expressions for scalar products of the so-called separate states, that are transfer matrix eigenstates or some simple generalization of them. In the higher rank case, left and right SoV bases are expected to be pseudo-orthogonal, that is for a given SoV co-vector \langle\underline{\mathbf{h}}\rangle⟨𝐡̲⟩, there could be more than one non-vanishing overlap \langle{\underline{\mathbf{h}}}|{\underline{\mathbf{k}}}\rangle⟨𝐡̲|𝐤̲⟩ with the vectors |{\underline{\mathbf{k}}}\rangle|𝐤̲⟩ of the chosen right SoV basis. For simplicity, we describe our method to get these pseudo-orthogonality overlaps in the fundamental representations of the \mathcal{Y}(gl_3)𝒴(gl3) lattice model with NN sites, a case of rank 2. The non-zero couplings between the co-vector and vector SoV bases are exactly characterized. While the corresponding SoV-measure stays reasonably simple and of possible practical use, we address the problem of constructing left and right SoV bases which do satisfy standard orthogonality (by standard we mean \langle{\underline{\mathbf{h}}}|{\underline{\mathbf{k}}}\rangle \propto \delta_{\underline{\mathbf{h}}, \underline{\mathbf{k}}}⟨𝐡̲|𝐤̲⟩∝δ𝐡̲,𝐤̲). In our approach, the SoV bases are constructed by using families of conserved charges. This gives us a large freedom in the SoV bases construction, and allows us to look for the choice of a family of conserved charges which leads to orthogonal co-vector/vector SoV bases. We first define such a choice in the case of twist matrices having simple spectrum and zero determinant. Then, we generalize the associated family of conserved charges and orthogonal SoV bases to generic simple spectrum and invertible twist matrices. Under this choice of conserved charges, and of the associated orthogonal SoV bases, the scalar products of separate states simplify considerably and take a form similar to the \mathcal{Y}(gl_2)𝒴(gl2) rank one case.

scholarly journals Conjectures on hidden Onsager algebra symmetries in interacting quantum lattice models

2021 ◽  
Vol 11 (3) ◽  
Author(s):  
Yuan Miao
Keyword(s):  
Lattice Models ◽  
Transfer Matrices ◽  
Xxz Model ◽  
Fusion Procedure ◽  
Root Of Unity ◽  
Integrable Lattice ◽  
Onsager Algebra ◽  
Cyclic Transfer ◽  
Integrable Lattice Models ◽  
Matrix Fusion

We conjecture the existence of hidden Onsager algebra symmetries in two interacting quantum integrable lattice models, i.e. spin-1/2 XXZ model and spin-1 Zamolodchikov-Fateev model at arbitrary root of unity values of the anisotropy. The conjectures relate the Onsager generators to the conserved charges obtained from semi-cyclic transfer matrices. The conjectures are motivated by two examples which are spin-1/2 XX model and spin-1 U(1)-invariant clock model. A novel construction of the semi-cyclic transfer matrices of spin-1 Zamolodchikov-Fateev model at arbitrary root of unity values of the anisotropy is carried out via the transfer matrix fusion procedure.

scholarly journals FLUCTUATING INTERFACES, SURFACE TENSION, AND CAPILLARY WAVES: AN INTRODUCTION

1992 ◽  
Vol 03 (05) ◽  
pp. 857-877 ◽  
Author(s):  
VLADIMIR PRIVMAN
Keyword(s):  
Surface Tension ◽  
Transfer Matrix ◽  
Lattice Models ◽  
Wave Model ◽  
Capillary Waves ◽  
Roughening Transition ◽  
Transfer Matrix Spectrum ◽  
Model Transfer ◽  
Matrix Spectrum ◽  
Long Cylinder

We present an introduction to modern theories of interfacial fluctuations and the associated interfacial parameters: surface tension and surface stiffness, as well as their interpretation within the capillary wave model. Transfer matrix spectrum properties due to fluctuation of an interface in a long-cylinder geometry are reviewed. The roughening transition and properties of rigid interfaces below the roughening temperature in 3d lattice models are surveyed with emphasis on differences in fluctuations and transfer matrix spectral properties of rigid vs. rough interfaces.

scholarly journals Symmetry resolved entanglement in gapped integrable systems: a corner transfer matrix approach

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Sara Murciano ◽  
Giuseppe Di Giulio ◽  
Pasquale Calabrese
Keyword(s):  
Transfer Matrix ◽  
Spin Chain ◽  
Lattice Models ◽  
Matrix Approach ◽  
Integrable Lattice ◽  
Transfer Matrix Approach ◽  
Harmonic Chain ◽  
Integrable Lattice Models ◽  
Exact Correlation ◽  
Harmonic System

We study the symmetry resolved entanglement entropies in gapped integrable lattice models. We use the corner transfer matrix to investigate two prototypical gapped systems with a U(1) symmetry: the complex harmonic chain and the XXZ spin-chain. While the former is a free bosonic system, the latter is genuinely interacting. We focus on a subsystem being half of an infinitely long chain. In both models, we obtain exact expressions for the charged moments and for the symmetry resolved entropies. While for the spin chain we found exact equipartition of entanglement (i.e. all the symmetry resolved entropies are the same), this is not the case for the harmonic system where equipartition is effectively recovered only in some limits. Exploiting the gaussianity of the harmonic chain, we also develop an exact correlation matrix approach to the symmetry resolved entanglement that allows us to test numerically our analytic results.

scholarly journals Separation of variables bases for integrable $gl_{\mathcal{M}|\mathcal{N}}$ and Hubbard models

2020 ◽  
Vol 9 (4) ◽  
Author(s):  
Jean Michel Maillet ◽  
Giuliano Niccoli ◽  
Louis Vignoli
Keyword(s):  
Boundary Conditions ◽  
Hubbard Model ◽  
Spectral Problem ◽  
Transfer Matrix ◽  
Separation Of Variables ◽  
Integrable Models ◽  
Simple Spectrum ◽  
Transfer Matrices ◽  
Matrix Eigenvalue ◽  
Twisted Boundary Conditions

We construct quantum Separation of Variables (SoV) bases for both the fundamental inhomogeneous % gl_{\mathcal{M}|\mathcal{N}}glℳ|𝒩 supersymmetric integrable models and for the inhomogeneous Hubbard model both defined with quasi-periodic twisted boundary conditions given by twist matrices having simple spectrum. The SoV bases are obtained by using the integrable structure of these quantum models, i.e. the associated commuting transfer matrices, following the general scheme introduced in [1]; namely, they are given by set of states generated by the multiple actions of the transfer matrices on a generic co-vector. The existence of such SoV bases implies that the corresponding transfer matrices have non-degenerate spectrum and that they are diagonalizable with simple spectrum if the twist matrices defining the quasi-periodic boundary conditions have that property. Moreover, in these SoV bases the resolution of the transfer matrix eigenvalue problem leads to the resolution of the full spectral problem, i.e. both eigenvalues and eigenvectors. Indeed, to any eigenvalue is associated the unique (up to a trivial overall normalization) eigenvector whose wave-function in the SoV bases is factorized into products of the corresponding transfer matrix eigenvalue computed on the spectrum of the separated variables. As an application, we characterize completely the transfer matrix spectrum in our SoV framework for the fundamental gl_{1|2}gl1|2 supersymmetric integrable model associated to a special class of twist matrices. From these results we also prove the completeness of the Bethe Ansatz for that case. The complete solution of the spectral problem for fundamental inhomogeneous gl_{\mathcal{M}|\mathcal{N}}glℳ|𝒩 supersymmetric integrable models and for the inhomogeneous Hubbard model under the general twisted boundary conditions will be addressed in a future publication.

scholarly journals Transfer matrix spectrum for cyclic representations of the 6-vertex reflection algebra II

2018 ◽  
Vol 5 (3) ◽  
Author(s):  
Jean Michel Maillet ◽  
Giuliano Niccoli ◽  
Baptiste Pezelier
Keyword(s):  
Boundary Conditions ◽  
Spectral Problem ◽  
Transfer Matrix ◽  
Separation Of Variables ◽  
General Boundary ◽  
Triangular Form ◽  
Transfer Matrix Spectrum ◽  
Lax Operator ◽  
Matrix Spectrum ◽  
Reflection Algebra

This article is a direct continuation of where we begun the study of the transfer matrix spectral problem for the cyclic representations of the trigonometric 6-vertex reflection algebra associated to the Bazhanov-Stroganov Lax operator. There we addressed this problem for the case where one of the KK-matrices describing the boundary conditions is triangular. In the present article we consider the most general integrable boundary conditions, namely the most general boundary KK-matrices satisfying the reflection equation. The spectral analysis is developed by implementing the method of Separation of Variables (SoV). We first design a suitable gauge transformation that enable us to put into correspondence the spectral problem for the most general boundary conditions with another one having one boundary KK-matrix in a triangular form. In these settings the SoV resolution can be obtained along an extension of the method described in . The transfer matrix spectrum is then completely characterized in terms of the set of solutions to a discrete system of polynomial equations in a given class of functions and equivalently as the set of solutions to an analogue of Baxter’s T-Q functional equation. We further describe scalar product properties of the separate states including eigenstates of the transfer matrix.

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