add some references

Author: lkdvos

docs/src/assets/mpskit.bib

@@ -59,6 +59,23 @@ @article{crotti2024
   keywords = {Condensed Matter - Disordered Systems and Neural Networks,Condensed Matter - Statistical Mechanics}
 }
 
+@misc{dempsey2025,
+  title = {Infinite Matrix Product States for \$(1+1)\$-Dimensional Gauge Theories},
+  author = {Dempsey, Ross and Gl{\"u}ck, Anna-Maria E. and Pufu, Silviu S. and S{\o}gaard, Benjamin T.},
+  year = 2025,
+  month = aug,
+  number = {arXiv:2508.16363},
+  eprint = {2508.16363},
+  primaryclass = {hep-th},
+  publisher = {arXiv},
+  doi = {10.48550/arXiv.2508.16363},
+  url = {http://arxiv.org/abs/2508.16363},
+  abstract = {We present a matrix product operator construction that allows us to represent the lattice Hamiltonians of (abelian or non-abelian) gauge theories in a local and manifestly translationinvariant form. In particular, we use symmetric matrix product states and introduce linkenhanced matrix product operators (LEMPOs) that can act on both the physical and virtual spaces of the matrix product states. This construction allows us to study Hamiltonian lattice gauge theories on infinite lattices. As examples, we show how to implement this method to study the massless and massive one-flavor Schwinger model and adjoint QCD2.},
+  archiveprefix = {arXiv},
+  langid = {english},
+  keywords = {Condensed Matter - Strongly Correlated Electrons,High Energy Physics - Lattice,High Energy Physics - Theory}
+}
+
 @article{devos2022,
   title = {Haldane Gap in the {{SU}}(3) [3 0 0] {{Heisenberg}} Chain},
   author = {Devos, Lukas and Vanderstraeten, Laurens and Verstraete, Frank},
@@ -165,6 +182,22 @@ @article{jeckelmann2002
   abstract = {A density-matrix renormalization-group (DMRG) method for calculating dynamical properties and excited states in low-dimensional lattice quantum many-body systems is presented. The method is based on an exact variational principle for dynamical correlation functions and the excited states contributing to them. This dynamical DMRG is an alternate formulation of the correction vector DMRG but is both simpler and more accurate. The finite-size scaling of spectral functions is discussed and a method for analyzing the scaling of dense spectra is described. The key idea of the method is a size-dependent broadening of the spectrum. The dynamical DMRG and the finite-size scaling analysis are demonstrated on the optical conductivity of the one-dimensional Peierls-Hubbard model. Comparisons with analytical results show that the spectral functions of infinite systems can be reproduced almost exactly with these techniques. The optical conductivity of the Mott-Peierls insulator is investigated and it is shown that its spectrum is qualitatively different from the simple spectra observed in Peierls (band) insulators and one-dimensional Mott-Hubbard insulators.}
 }
 
+@misc{kirchner2025,
+  title = {Phases of {{Interacting Fibonacci Anyons}} on a {{Ladder}} at {{Half-Filling}}},
+  author = {Kirchner, Nico and Moessner, Roderich and Pollmann, Frank and {Gammon-Smith}, Adam},
+  year = 2025,
+  month = jul,
+  number = {arXiv:2507.22115},
+  eprint = {2507.22115},
+  primaryclass = {cond-mat},
+  publisher = {arXiv},
+  doi = {10.48550/arXiv.2507.22115},
+  url = {http://arxiv.org/abs/2507.22115},
+  abstract = {Two-dimensional many-body quantum systems can exhibit topological order and support collective excitations with anyonic statistics different from the usual fermionic or bosonic ones. With the emergence of these exotic point-like particles, it is natural to ask what phases can arise in interacting many-anyon systems. To study this topic, we consider the particular case of Fibonacci anyons subject to an anyonic tight-binding model with nearest-neighbor repulsion on a two-leg ladder. Focusing on the case of half-filling, for low interaction strengths an ''anyonic'' metal is found, whereas for strong repulsion, the anyons form an insulating charge-density wave. Within the latter regime, we introduce an effective one-dimensional model up to sixth order in perturbation theory arising from anyonic superexchange processes. We numerically identify four distinct phases of the effective model, which we characterize using matrix product state methods. These include both the ferro- and antiferromagnetic golden chain, a \$\textbackslash mathbb\textbraceleft Z\textbraceright\_2\$ phase, and an incommensurate phase.},
+  archiveprefix = {arXiv},
+  keywords = {Condensed Matter - Strongly Correlated Electrons,Quantum Physics}
+}
+
 @article{mortier2025,
   title = {Fermionic Tensor Network Methods},
   author = {Mortier, Quinten and Devos, Lukas and Burgelman, Lander and Vanhecke, Bram and Bultinck, Nick and Verstraete, Frank and Haegeman, Jutho and Vanderstraeten, Laurens},

src/algorithms/fixedpoint.jl

@@ -8,26 +8,30 @@ Compute the fixedpoint of a linear operator `A` using the specified eigensolver
 fixedpoint is assumed to be unique.
 """
 function fixedpoint(A, x₀, which::Symbol, alg::Lanczos)
-    vals, vecs, info = eigsolve(A, x₀, 1, which, alg)
+    A′, x₀′ = prepare_operator!!(A, x₀)
+    vals, vecs, info = eigsolve(A′, x₀′, 1, which, alg)
 
-    if info.converged == 0
+    info.converged == 0 &&
         @warnv 1 "fixedpoint not converged after $(info.numiter) iterations: normres = $(info.normres[1])"
-    end
 
-    return vals[1], vecs[1]
+    λ = vals[1]
+    v = unprepare_operator!!(vecs[1], A, x₀)
+
+    return λ, v
 end
 
 function fixedpoint(A, x₀, which::Symbol, alg::Arnoldi)
-    TT, vecs, vals, info = schursolve(A, x₀, 1, which, alg)
+    A′, x₀′ = prepare_operator!!(A, x₀)
+    TT, vecs, vals, info = schursolve(A′, x₀′, 1, which, alg)
 
-    if info.converged == 0
+    info.converged == 0 &&
         @warnv 1 "fixedpoint not converged after $(info.numiter) iterations: normres = $(info.normres[1])"
-    end
-    if size(TT, 2) > 1 && TT[2, 1] != 0
-        @warnv 1 "non-unique fixedpoint detected"
-    end
+    size(TT, 2) > 1 && TT[2, 1] != 0 && @warnv 1 "non-unique fixedpoint detected"
+
+    λ = vals[1]
+    v = unprepare_operator!!(vecs[1], A, x₀)
 
-    return vals[1], vecs[1]
+    return λ, v
 end
 
 function fixedpoint(A, x₀, which::Symbol; kwargs...)