Publications

Order by: publication date number of citations

• Mapping a dissipative quantum spin chain onto a generalized Coulomb gas

  Oscar Bouverot-Dupuis

  SciPost Phys. 17, 130 (2024) · published 11 November 2024 | Toggle abstract · pdf

  An XXZ spin chain at zero magnetization is subject to spatially correlated baths acting as dissipation. We show that the low-energy excitations of this model are described by a dissipative sine-Gordon field theory, i.e. a sine-Gordon action with an additional long-range interaction emerging from dissipation. The field theory is then exactly mapped onto a generalized Coulomb gas which, in addition to the usual integer charges, displays half-integer charges that originate from the dissipative baths. These new charges come in pairs linked by a charge independent logarithmic interaction. In the Coulomb gas picture, we identify a Berezinsky–Kosterlitz–Thouless-like phase transition corresponding to the binding of charges and derive the associated perturbative renormalization group equations. For superohmic baths, the transition is due to the binding of the integer charges, while for subohmic baths, it is due to the binding of the half-integer charges, thereby signaling a dissipation-induced transition.

  1 citation

• Smuggling critique into impact: Research design principles for critical and actionable migration research

  Maybritt Jill Alpes

  Mig. Pol. 4, 004 (2025) · published 12 June 2025 | Toggle abstract · pdf

  This article introduces critical and actionable migration research as an approach for scholars seeking to mobilize their epistemic resources to resist migration laws and policies that violate human rights principles in the short and medium term. While academia is increasingly shaped by a neoliberal “impact agenda,” violence at physical and administrative borders, as well human rights violations continue to intensify - raising questions about the potential role of academic knowledge in resisting these dynamics. Using ideal types as simplified analytical constructs, the article suggests that the limited transformative potential of academic knowledge stems from a persistant dichotomy: applied research is often not critical and critical research is often not actionable. Overcoming this dichotomy, critical and actionable migration research advances structural transformations and reframes while simultaneously remaining actionable for state actors in the short and medium term. As such, critical and actionable migration research is not applied research, nor devoid of theoretical considerations. Using the metaphor of smuggling, this article asks how migration researchers can reclaim the meaning of “impact” so that it contains the grains of critique that resist border violence and human rights violations in the short and medium term. The article’s answer is based on autobiographical explorations of what it means for an anthropologist to produce knowledge on migration from within law faculties and as policy officer and research consultant for human and refugee rights organizations. Based on this material, the article argues that “impact” is nothing to be “done” once the research is completed. To engage in critical and actionable migration research, scholars should instead theorize transformative knowledge encounters between academics and practitioners as integral parts of the research design. After a discussion of the autobiographical data and a conceptual discussion of transformative knowledge encounters, the article highlights three specific research design principles for critical and actionable migration research: (1) building innovative knowledge alliances, (2) theorizing knowledge needs, and (3) brokering the validity of truth claims.

  1 citation

• Codebase release 1.0 for TorchGPE

  Lorenzo Fioroni, Luca Gravina, Justyna Stefaniak, Alexander Baumgärtner, Fabian Finger, Davide Dreon, Tobias Donner

  SciPost Phys. Codebases 38-r1.0 (2024) · published 6 November 2024 | Toggle abstract · src

  TorchGPE is a general-purpose Python package developed for solving the Gross-Pitaevskii equation (GPE). This solver is designed to integrate wave functions across a spectrum of linear and non-linear potentials. A distinctive aspect of TorchGPE is its modular approach, which allows the incorporation of arbitrary self-consistent and time-dependent potentials, e.g., those relevant in many-body cavity QED models. The package employs a symmetric split-step Fourier propagation method, effective in both real and imaginary time. In our work, we demonstrate a significant improvement in computational efficiency by leveraging GPU computing capabilities. With the integration of the latter technology, TorchGPE achieves a substantial speed-up with respect to conventional CPU-based methods, greatly expanding the scope and potential of research in this field.

  1 citation

• Simulation of the 1d XY model on a quantum computer

  Marc Farreras, Alba Cervera-Lierta

  SciPost Phys. Lect. Notes 95 (2025) · published 11 June 2025 | Toggle abstract · pdf

  The field of quantum computing has grown fast in recent years, both in theoretical advancements and the practical construction of quantum computers. These computers were initially proposed, among other reasons, to efficiently simulate and comprehend the complexities of quantum physics. In this paper, we present a comprehensive scheme for the exact simulation of the 1-D XY model on a quantum computer. We successfully diagonalize the proposed Hamiltonian, enabling access to the complete energy spectrum. Furthermore, we propose a novel approach to design a quantum circuit to perform exact time evolution. Among all the possibilities this opens, we compute the ground and excited state energies for the symmetric XY model with spin chains of $n=4$ and $n=8$ spins. Further, we calculate the expected value of transverse magnetization for the ground state in the transverse Ising model. Both studies allow the observation of a quantum phase transition from an antiferromagnetic to a paramagnetic state. Additionally, we have simulated the time evolution of the state all spins up in the transverse Ising model. The scalability and high performance of our algorithm make it an ideal candidate for benchmarking purposes, while also laying the foundation for simulating other integrable models on quantum computers.

  1 citation

• Codebase release 2.0 for sauce

  Caleb Marshall

  SciPost Phys. Codebases 37-r2.0 (2024) · published 6 November 2024 | Toggle abstract · src

  Low energy nuclear physics experiments are transitioning towards fully digital data acquisition systems. Realizing the gains in flexibility afforded by these systems relies on equally flexible data reduction techniques. In this paper, methods utilizing data frames and in-memory techniques to work with data, including data from self-triggering, digital data acquisition systems, are discussed within the context of a Python package, sauce. It is shown that data frame operations can encompass common analysis needs and allow interactive data analysis. Two event building techniques, dubbed referenced and referenceless event building, are shown to provide a means to transform raw list mode data into correlated multi-detector events. These techniques are demonstrated in the analysis of two example data sets.

  1 citation

• Implementing Transverse Momentum Dependent splitting functions in Parton Branching evolution equations

  Lissa Keersmaekers

  SciPost Phys. Proc. 8, 127 (2022) · published 13 July 2022 | Toggle abstract · pdf

  The Parton Branching (PB) approach describes the evolution of transverse momentum dependent (TMD) parton densities. We propose to extend the PB method by including TMD splitting functions, instead of the DGLAP splitting functions which assume strong ordering in transverse momentum. We present the evolution equations and their numerical solution, which is the first Monte Carlo implementation including TMD splitting functions.

  1 citation

• Geometric constructions of generalized dual-unitary circuits from biunitarity

  Michael A. Rampp, Suhail A. Rather, Pieter W. Claeys

  SciPost Phys. 18, 182 (2025) · published 10 June 2025 | Toggle abstract · pdf

  We present a general framework for constructing solvable lattice models of chaotic many-body quantum dynamics with multiple unitary directions using biunitary connections. We show that a network of biunitary connections on the kagome lattice naturally defines a multi-unitary circuit, where three 'arrows of time' directly reflect the lattice symmetry. These models unify various constructions of hierarchical dual-unitary and triunitary gates and present new families of models with solvable correlations and entanglement dynamics. Using multilayer constructions of biunitary connections, we additionally introduce multilayer circuits with monoclinic symmetry and higher level hierarchical dual-unitary solvability and discuss their (non-)ergodicity. Our work demonstrates how different classes of solvable models can be understood as arising from different geometric structures in spacetime.

  1 citation

• Particle dynamics on torsional galilean spacetimes

  José Figueroa-O'Farrill, Can Görmez, Dieter Van den Bleeken

  SciPost Phys. 14, 059 (2023) · published 4 April 2023 | Toggle abstract · pdf

  We study free particle motion on homogeneous kinematical spacetimes of galilean type. The three well-known cases of Galilei and (A)dS-Galilei spacetimes are included in our analysis, but our focus will be on the previously unexplored torsional galilean spacetimes. We show how in well-chosen coordinates free particle motion becomes equivalent to the dynamics of a damped harmonic oscillator, with the damping set by the torsion. The realization of the kinematical symmetry algebra in terms of conserved charges is subtle and comes with some interesting surprises, such as a homothetic version of hamiltonian vector fields and a corresponding generalization of the Poisson bracket. We show that the Bargmann extension is universal to all galilean kinematical symmetries, but also that it is no longer central for nonzero torsion. We also present a geometric interpretation of this fact through the Eisenhart lift of the dynamics.

  1 citation

• 2d dualities from 4d

  Jiaqun Jiang, Satoshi Nawata, Jiahao Zheng

  SciPost Phys. 18, 180 (2025) · published 6 June 2025 | Toggle abstract · pdf

  We find new $\mathcal{N}=(2,2)$ and $\mathcal{N}=(0,2)$ dualities through the twisted compactifications of 4d supersymmetric theories on $S^2$. Our findings include dualities for both $\mathcal{N}=(2,2)$ and $\mathcal{N}=(0,2)$ non-Abelian gauge theories, as well as $\mathcal{N}=(0,2)$ Gauge/Landau-Ginzburg duality.

  1 citation

• Central exclusive diffractive production of axial-vector $f_{1}$ mesons in proton-proton collisions

  Piotr Lebiedowicz, Josef Leutgeb, Otto Nachtmann, Anton Rebhan, Antoni Szczurek

  SciPost Phys. Proc. 8, 121 (2022) · published 13 July 2022 | Toggle abstract · pdf

  Exclusive production of axial-vector $f_{1}(1285)$ meson in proton-proton collisions via pomeron-pomeron fusion within the tensor-pomeron approach is discussed. Two ways to construct the pomeron-pomeron-$f_{1}$ coupling are presented. We adjust the parameters of our model to the WA102 experimental data and compare with predictions of the Sakai-Sugimoto model. Predictions for LHC experiments are given.

  1 citation