Publications

Order by: publication date number of citations

• Anomalies of coset non-invertible symmetries

  Po-Shen Hsin, Ryohei Kobayashi, Carolyn Zhang

  SciPost Phys. 20, 006 (2026) · published 13 January 2026 | Toggle abstract · pdf

  Anomalies of global symmetries provide important information on the quantum dynamics. We show the dynamical constraints can be organized into three classes: genuine anomalies, fractional topological responses, and integer responses that can be realized in symmetry-protected topological (SPT) phases. Coset symmetry can be present in many physical systems including quantum spin liquids, and the coset symmetry can be a non-invertible symmetry. We introduce twists in coset symmetries, which modify the fusion rules and the generalized Frobenius-Schur indicators. We call such coset symmetries twisted coset symmetries, and they are labeled by the quadruple $(G,K,\omega_{D+1},\alpha_D)$ in $D$ spacetime dimensions where $G$ is a group and $K\subset G$ is a discrete subgroup, $\omega_{D+1}$ is a $(D+1)$-cocycle for group $G$, and $\alpha_{D}$ is a $D$-cochain for group $K$. We present several examples with twisted coset symmetries using lattice models and field theory, including both gapped and gapless systems (such as gapless symmetry-protected topological phases). We investigate the anomalies of general twisted coset symmetry, which presents obstructions to realizing the coset symmetry in (gapped) symmetry-protected topological phases. We show that finite coset symmetry $G/K$ becomes anomalous when $G$ cannot be expressed as the bicrossed product $G=H\Join K$, and such anomalous coset symmetry leads to symmetry-enforced gaplessness in generic spacetime dimensions. We illustrate examples of anomalous coset symmetries with $A_5/\Z_2$ symmetry, with realizations in lattice models.

  1 citation

• Dynamic models for two nonreciprocally coupled fields: A microscopic derivation for zero, one, and two conservation laws

  Kristian Blom, Uwe Thiele, Aljaž Godec

  SciPost Phys. 20, 005 (2026) · published 13 January 2026 | Toggle abstract · pdf

  We construct dynamic models governing two nonreciprocally coupled fields for several cases with zero, one, and two conservation laws. Starting from two microscopic nonreciprocally coupled Ising models, and using the mean-field approximation, we obtain closed-form evolution equations for the spatially resolved magnetization in each lattice. Only allowing for single spin-flip dynamics, the macroscopic equations in the thermodynamic limit are closely related to the nonreciprocal Allen-Cahn equations, i.e., conservation laws are absent. Likewise, only accounting for spin-exchange dynamics within each lattice, the thermodynamic limit yields equations similar to the nonreciprocal Cahn-Hilliard model, i.e., with two conservation laws. In the case of spin-exchange dynamics within and between the two lattices, we obtain two nonreciprocally coupled equations that add up to one conservation law. For each of these cases, we systematically map out the linear instabilities that can arise. Moreover, combining the different dynamics gives a large number of further models. Our results provide a microscopic foundation for a broad class of nonreciprocal field theories, establishing a direct link between non-equilibrium statistical mechanics and macroscopic continuum descriptions.

• Extrapolating jet radiation with autoregressive transformers

  Anja Butter, François Charton, Javier Mariño Villadamigo, Ayodele Ore, Tilman Plehn, Jonas Spinner

  SciPost Phys. 20, 004 (2026) · published 12 January 2026 | Toggle abstract · pdf

  Generative networks are an exciting tool for fast LHC event generation with fixed number of particles. Autoregressive transformers allow us to generate events containing variable numbers of particles, very much in line with the physics of QCD jet radiation, and offer the possibility to generalize to higher multiplicities. We show how transformers can learn a factorized likelihood for jet radiation and extrapolate in terms of the number of generated jets. For this extrapolation, bootstrapping training data and training with modifications of the likelihood loss can be used.

• Density of states correlations in Lévy Rosenzweig-Porter model via supersymmetry approach

  Elizaveta Safonova, Aleksey Lunkin, Mikhail Feigel'man

  SciPost Phys. 20, 003 (2026) · published 12 January 2026 | Toggle abstract · pdf

  We studied global density-of-states correlation function $R(\omega)$ for Lévy-Rosenzweig-Porter random matrix ensemble in the non-ergodic extended phase. Using an extension of Efetov's supersymmetry approach we calculated $R(\omega)$ exactly in all relevant ranges of $\omega$. At relatively low $\omega ≤ \Gamma$ (with $\Gamma \gg \Delta$ being the effective miniband width) we found GUE-type oscillations with period of level spacing $\Delta$, decaying exponentially at the Thouless energy scale $E_{Th} = \sqrt{\Delta \Gamma/2\pi}$. At high energies $\omega \gg E_{Th}$ our results coincide with those obtained in [A. V. Lunkin and K. Tikhonov, SciPost Phys. 19, 015 (2025)] via cavity equation approach. Inverse of the effective miniband width, $1/\Gamma$, is shown to be given by the average of the local decay times over Lévy distribution.

• Coherent generation and protection of anticoherent spin states

  Jérôme Denis, Colin Read, John Martin

  SciPost Phys. Core 9, 001 (2026) · published 12 January 2026 | Toggle abstract · pdf

  We report the first protocol specifically designed to generate anticoherent spin-$j$ states at different orders. The protocol consists of cycles of a rotation pulse about an axis followed by a squeezing pulse in a perpendicular direction. To protect these states, we develop dynamical decoupling techniques using group-based sequence design and the dynamically corrected gate formalism. We analyze key sources of dephasing, disorder, and dipole-dipole interactions and assess the effectiveness of our methods in preserving coherence. Potential applications of the produced anticoherent spin states include quantum sensing and studies related to quantum entanglement.

• The ITransverse.jl library for transverse tensor network contractions

  Stefano Carignano

  SciPost Phys. Codebases 63 (2026) · published 9 January 2026 | Toggle abstract · pdf

  Transverse contraction methods are extremely promising tools for the efficient contraction of tensor networks associated with the time evolution of quantum many-body systems, allowing in some cases to circumvent the entanglement barrier that would normally prevent the study of quantum dynamics with classical resources. We present here the ITransverse.jl package, written in Julia and based on ITensors.jl, containing several of these high-level algorithms, including novel prescriptions for efficient truncations of temporal matrix product states.

  1 citation

• Codebase release 0.24 for ITransverse.jl

  Stefano Carignano

  SciPost Phys. Codebases 63-r0.24 (2026) · published 9 January 2026 | Toggle abstract · src

  Transverse contraction methods are extremely promising tools for the efficient contraction of tensor networks associated with the time evolution of quantum many-body systems, allowing in some cases to circumvent the entanglement barrier that would normally prevent the study of quantum dynamics with classical resources. We present here the ITransverse.jl package, written in Julia and based on ITensors.jl, containing several of these high-level algorithms, including novel prescriptions for efficient truncations of temporal matrix product states.

  1 citation

• Codebase release 3.0 for GoSam

  Jens Braun, Benjamin Campillo, Gudrun Heinrich, Marius Höfer, Stephen P. Jones, Matthias Kerner, Jannis Lang, Vitaly Magerya

  SciPost Phys. Codebases 62-r3.0 (2026) · published 9 January 2026 | Toggle abstract · src

  We present a major update of the one-loop generator GoSam, containing performance improvements as well as new features, in particular functionalities that facilitate calculations beyond the Standard Model in Effective Field Theory frameworks.

  2 citations

• One-loop calculations in effective field theories with GoSam-3.0

  Jens Braun, Benjamin Campillo, Gudrun Heinrich, Marius Höfer, Stephen P. Jones, Matthias Kerner, Jannis Lang, Vitaly Magerya

  SciPost Phys. Codebases 62 (2026) · published 9 January 2026 | Toggle abstract · pdf

  We present a major update of the one-loop generator GoSam, containing performance improvements as well as new features, in particular functionalities that facilitate calculations beyond the Standard Model in Effective Field Theory frameworks.

  2 citations

• The fate of entanglement

  Gilles Parez, William Witczak-Krempa

  SciPost Phys. 20, 002 (2026) · published 8 January 2026 | Toggle abstract · pdf

  Quantum entanglement manifests itself in non-local correlations between the constituents of a system. In its simplest realization, a measurement on one subsystem is affected by a prior measurement on its partner, irrespective of their separation. For multiple parties, purely collective types of entanglement exist but their detection, even theoretically, remains an outstanding open question. Here, we argue that all forms of multipartite entanglement entirely disappear during the typical evolution of a physical state as it heats up, evolves in time in a large family of dynamical protocols, or as its parts become separated. We focus on the generic case where the system interacts with an environment. These results mainly follow from the geometry of the entanglement-free continent in the space of physical states, and hold in great generality. We illustrate these phenomena with a frustrated molecular quantum magnet in and out of equilibrium, and a quantum spin chain. In contrast, if the particles are fermions, such as electrons, another notion of entanglement exists that protects bipartite quantum correlations. However, genuinely collective fermionic entanglement disappears during typical evolution, thus sharing the same fate as in bosonic systems. These findings provide fundamental knowledge about the structure of entanglement in quantum matter and architectures, paving the way for its manipulation.