Publications

Order by: publication date number of citations

• Gauging non-invertible symmetries on the lattice

  Sahand Seifnashri, Shu-Heng Shao, Xinping Yang

  SciPost Phys. 19, 063 (2025) · published 29 August 2025 | Toggle abstract · pdf

  We provide a general prescription for gauging finite non-invertible symmetries in 1+1d lattice Hamiltonian systems. Our primary example is the Rep(D$_8$) fusion category generated by the Kennedy-Tasaki transformation, which is the simplest anomaly-free non-invertible symmetry on a spin chain of qubits. We explicitly compute its lattice F-symbols and illustrate our prescription for a particular (non-maximal) gauging of this symmetry. In our gauging procedure, we introduce two qubits around each link, playing the role of "gauge fields" for the non-invertible symmetry, and impose novel Gauss's laws. Similar to the Kramers-Wannier transformation for gauging an ordinary $\mathbb{Z}_2$, our gauging can be summarized by a gauging map, which is part of a larger, continuous non-invertible cosine symmetry.

  5 citations

• A quantum annealing protocol to solve the nuclear shell model

  Emanuele Costa, Axel Pérez-Obiol, Javier Menéndez, Arnau Rios, Artur García-Sáez, Bruno Juliá-Díaz

  SciPost Phys. 19, 062 (2025) · published 29 August 2025 | Toggle abstract · pdf

  The nuclear shell model accurately describes the structure and dynamics of atomic nuclei. However, the exponential scaling of the basis size with the number of degrees of freedom hampers a direct numerical solution for heavy nuclei. In this work, we present a quantum annealing protocol to obtain nuclear ground states. We propose a tailored driver Hamiltonian that preserves a large gap and validate our approach in a dozen nuclei with basis sizes up to $10^5$ using classical simulations of the annealing evolution. We explore the relation between the spectral gap and the total time of the annealing protocol, assessing its accuracy by comparing the fidelity and energy relative error to classical benchmarks. While the nuclear Hamiltonian is non-local and thus challenging to implement in current setups, the estimated computational cost of our annealing protocol on quantum circuits is polynomial in the single-particle basis size, paving the way to study heavier nuclei.

  1 citation

• Approach to the separatrix with eccentric orbits

  Guillaume Lhost, Geoffrey Compère

  SciPost Phys. Core 8, 059 (2025) · published 29 August 2025 | Toggle abstract · pdf

  Eccentric binary compact mergers are prime targets of current and future gravitational wave observatories. In the small mass ratio expansion, post-adiabatic inspirals have been modeled up to the separatrix, where first-principle modeling currently ends. In this paper, we derive the analytic late time solution to the adiabatic inspiral in terms of self-force coefficients at the separatrix. We identify the role of the Lambert $W_{-1}$ function as a key mathematical ingredient in the approach to the separatrix.

  2 citations

• Boundary SymTFT

  Lakshya Bhardwaj, Christian Copetti, Daniel Pajer, Sakura Schäfer-Nameki

  SciPost Phys. 19, 061 (2025) · published 28 August 2025 | Toggle abstract · pdf

  We study properties of boundary conditions (BCs) in theories with categorical (or non-invertible) symmetries. We describe how the transformation properties, or (generalized) charges, of BCs are captured by topological BCs of Symmetry Topological Field Theory (SymTFT), which is a topological field theory in one higher spacetime dimension. As an application of the SymTFT characterization, we discuss the symmetry properties of boundary conditions for (1+1)d gapped and gapless phases. We provide a number of concrete examples in spacetime dimensions $d=2,3$. We furthermore expand the lattice description for (1+1)d anyon chains with categorical symmetries to include boundary conditions carrying arbitrary 1-charges under the symmetry.

  4 citations

• A localising AdS$_3$ sigma model

  Lorenz Eberhardt, Matthias R. Gaberdiel

  SciPost Phys. 19, 060 (2025) · published 28 August 2025 | Toggle abstract · pdf

  We construct a CFT with $\mathfrak{sl}(2,\mathbb{R})_k$ symmetry at the 'tensionless' point $k=3$, which is distinct from the usual $\mathrm{SL}(2,\mathbb{R})_{k=3}$ WZW model. This new CFT is much simpler than the generic WZW model: in particular its three-point functions feature momentum-conserving delta functions, and its higher-point functions localise to covering map configurations in moduli space. We establish the consistency of the theory by explicitly deriving the four-point function from the three-point data via a sum over conformal blocks. The main motivation for our construction comes from holography, and we show that various simple supersymmetric holographic dualities for $k_{\rm s}=1$ ($k=3$) can be constructed by replacing the $\mathrm{AdS}_3$ factor on the worldsheet with this alternative theory. This includes in particular the prototypical case of $\mathrm{AdS}_3 × \mathrm{S}^3 × \mathbb{T}^4$, as well as the recently discussed example of $\mathrm{AdS}_3 × \mathrm{S}^3 × \mathrm{S}^3 × \mathrm{S}^1$. However, our analysis does not require supersymmetry and also applies to bosonic ${\rm AdS}_3$ backgrounds (at $k=3$).

  4 citations

• Gauge theory for topological waves in continuum fluids with odd viscosity

  Keisuke Fujii, Yuto Ashida

  SciPost Phys. Core 8, 058 (2025) · published 28 August 2025 | Toggle abstract · pdf

  We consider two-dimensional continuum fluids with odd viscosity under a chiral body force. The chiral body force makes the low-energy excitation spectrum of the fluids gapped, and the odd viscosity allows us to introduce the first Chern number of each energy band in the fluids. Employing a mapping between hydrodynamic variables and U(1) gauge field strengths, we derive a U(1) gauge theory for topologically nontrivial waves. The resulting U(1) gauge theory is given by the Maxwell-Chern-Simons theory with an additional term associated with odd viscosity. We then explicitly solve the equations of motion for the gauge fields in the presence of the boundary and find edge mode solutions. We finally confirm the bulk-boundary correspondence in the context of continuum systems.

• Dipolar magnetostirring protocol for three-well atomtronic circuits

  Héctor Briongos-Merino, Felipe Isaule, Montserrat Guilleumas, Bruno Juliá-Díaz

  SciPost Phys. 19, 059 (2025) · published 27 August 2025 | Toggle abstract · pdf

  We propose a magnetostirring protocol to create persistent currents on an annular system. Under this protocol, polar bosons confined in a three-well ring circuit reach a state with high average circulation. We model the system with an extended Bose-Hubbard Hamiltonian and show that the protocol can create circulation in an atomtronic circuit for a range of tunable parameters. The performance and robustness of this scheme are examined, in particular considering different interaction regimes. We also present a method for predicting the optimal protocol parameters, which improves protocol's scalability and enables its application to systems with large numbers of bosons. This overcomes computational limitations and paves the way for exploring macroscopic quantum phenomena.

• Scattering theory of higher order topological phases

  R. Johanna Zijderveld, Isidora Araya Day, Anton R. Akhmerov

  SciPost Phys. 19, 058 (2025) · published 27 August 2025 | Toggle abstract · pdf

  The surface states of intrinsic higher order topological phases are protected by the spatial symmetries of a finite sample. This property makes the existing scattering theory of topological invariants inapplicable: the scattering geometry is either incompatible with the symmetry or does not probe the bulk topology. We resolve this obstacle by using a symmetric scattering geometry that probes transport from the inside to the outside of the sample. We demonstrate that the intrinsic higher order topology is captured by the flux dependence of the reflection matrix. Our finding follows from identifying the spectral flow of a flux line as a signature of higher order topology. We show how this scattering approach applies to several examples of higher order topological insulators and superconductors. Our theory provides an alternative approach for proving bulk-edge correspondence in intrinsic higher order topological phases, especially in the presence of disorder.

  1 citation

• Spin-$s$ $Q$-systems: Twist and open boundaries

  Yi-Jun He, Jue Hou, Yi-Chao Liu, Zi-Xi Tan

  SciPost Phys. Core 8, 057 (2025) · published 27 August 2025 | Toggle abstract · pdf

  In integrable spin chains, the spectral problem can be solved by the method of Bethe Ansatz, which transforms the problem of diagonalization of the Hamiltonian into the problem of solving a set of algebraic equations named Bethe equations. In this work, we systematically investigate the spin-$s$ XXX chain with twisted and open boundary conditions using the rational $Q$-system, which is a powerful tool to solve Bethe equations. We establish basic frameworks of the rational $Q$-system and confirm its completeness numerically in both cases. For twisted boundaries, we investigate the polynomiality conditions of the rational $Q$-system and derive physical conditions for singular solutions of Bethe equations. For open boundaries, we uncover novel phenomena such as hidden symmetries and boundary induced strings under specific boundary parameters. Hidden symmetries lead to the appearance of extra degeneracies in the Hilbert space, while the boundary induced string is a novel type of exact string configuration, whose length depends on the boundary magnetic fields. These findings, supported by both analytical and numerical evidences, offer new insights into the interplay between symmetries and boundary conditions.

• Resumming post-Minkowskian and post-Newtonian gravitational waveform expansions

  Andrea Cipriani, Giorgio Di Russo, Francesco Fucito, José Francisco Morales, Hasmik Poghosyan, Rubik Poghossian

  SciPost Phys. 19, 057 (2025) · published 26 August 2025 | Toggle abstract · pdf

  We derive formulae that resum, at a given order in the soft limit, the infinite series of Post-Minkowkian (small gravitational coupling) or Post-Newtonian (small velocities) corrections to the gravitational waveform produced by particles moving along a general (open or closed) trajectory in Schwarzschild geometry in the probe limit. Specifying to the case of circular orbits, we compute the wave form and the energy flux to order 30PN, and compare it against the available results in the literature. The results are based on a novel hypergeometric representation of the solutions of the Heun equation (and its confluence), that leads to a simple mathematical proof of the Heun connection formula.

  1 citation