Publications

Order by: publication date number of citations

• Thermodynamic Bethe Ansatz and generalised hydrodynamics in the sine-Gordon model

  Botond C. Nagy, Gábor Takács, Márton Kormos

  SciPost Phys. 16, 145 (2024) · published 4 June 2024 | Toggle abstract · pdf

  We set up a hydrodynamic description of the non-equilibrium dynamics of sine-Gordon quantum field theory for generic coupling. It is built upon an explicit form of the Bethe Ansatz description of general thermodynamic states, with the structure of the resulting coupled integral equations encoded in terms of graphical diagrams. The resulting framework is applied to derive results for the Drude weights of charge and energy. Quantities associated with the charge universally have fractal dependence on the coupling, which is notably absent from those associated with energy, a feature explained by the different roles played by reflective scattering in transporting these quantities. We then present far-from-equilibrium results, including explicit time evolution starting from bipartite initial states and dynamical correlation functions. Our framework can be applied to explore numerous other aspects of non-equilibrium dynamics, which opens the way to a wide array of theoretical studies and potential novel experimental predictions.

• One-shot holography

  Chris Akers, Adam Levine, Geoff Penington, Elizabeth Wildenhain

  SciPost Phys. 16, 144 (2024) · published 4 June 2024 | Toggle abstract · pdf

  Following the work of [J. High Energy Phys. 04, 062 (2021)], we define a generally covariant max-entanglement wedge of a boundary region B, which we conjecture to be the bulk region reconstructible from B. We similarly define a covariant min-entanglement wedge, which we conjecture to be the bulk region that can influence the state on B. We prove that the min- and max-entanglement wedges obey various properties necessary for this conjecture, such as nesting, inclusion of the causal wedge, and a reduction to the usual quantum extremal surface prescription in the appropriate special cases. These proofs rely on one-shot versions of the (restricted) quantum focusing conjecture (QFC) that we conjecture to hold. We argue that these QFCs imply a one-shot generalized second law (GSL) and quantum Bousso bound. Moreover, in a particular semiclassical limit we prove this one-shot GSL directly using algebraic techniques. Finally, in order to derive our results, we extend both the frameworks of one-shot quantum Shannon theory and state-specific reconstruction to finite-dimensional von Neumann algebras, allowing nontrivial centers.

• Search for light WIMP recoils on methane with NEWS-G

  Francisco A. Vazquez de Sola Fernandez on behalf of the NEWS-G collaboration

  SciPost Phys. Proc. 12, 073 (2024) · published 4 June 2024 | Toggle abstract · pdf

  The NEWS-G collaboration is searching for light dark matter using single-electron-threshold Spherical Proportional Counters (SPCs) filled with light gaseous targets (H, He, Ne). NEWS-G has built a new 140 cm diameter SPC equipped with a multi-anode ACHINOS sensor. Robust calibrations with a UV laser and an $\mathrm{^{37}}$Ar source were performed to characterize the detector response to low energy events and achieve statistical background rejection. This work presents preliminary results from physics data taken with methane, leading to world-leading spin-dependent sensitivity under 2 $\mathrm{GeV/c^{2}}$ WIMP masses.

• Fusion surface models: 2+1d lattice models from fusion 2-categories

  Kansei Inamura, Kantaro Ohmori

  SciPost Phys. 16, 143 (2024) · published 3 June 2024 | Toggle abstract · pdf

  We construct (2+1)-dimensional lattice systems, which we call fusion surface models. These models have finite non-invertible symmetries described by general fusion 2-categories. Our method can be applied to build microscopic models with, for example, anomalous or non-anomalous one-form symmetries, 2-group symmetries, or non-invertible one-form symmetries that capture non-abelian anyon statistics. The construction of these models generalizes the construction of the 1+1d anyon chains formalized by Aasen, Fendley, and Mong. Along with the fusion surface models, we also obtain the corresponding three-dimensional classical statistical models, which are 3d analogues of the 2d Aasen-Fendley-Mong height models. In the construction, the "symmetry TFTs" for fusion 2-category symmetries play an important role.

  1 citation

• CDMFT+HFD: An extension of dynamical mean field theory for nonlocal interactions applied to the single band extended Hubbard model

  Sarbajaya Kundu, David Sénéchal

  SciPost Phys. Core 7, 033 (2024) · published 3 June 2024 | Toggle abstract · pdf

  We examine the phase diagram of the extended Hubbard model on a square lattice, for both attractive and repulsive nearest-neighbor interactions, using CDMFT+HFD, a combination of Cluster Dynamical Mean Field theory (CDMFT) and a Hartree-Fock mean-field decoupling of the inter-cluster extended interaction. For attractive non-local interactions, this model exhibits a region of phase separation near half-filling, in the vicinity of which we find islands of d-wave superconductivity, decaying rapidly as a function of doping, with disconnected regions of extended s-wave order at smaller (higher) electron densities. On the other hand, when the extended interaction is repulsive, a Mott insulating state at half-filling is destabilized by hole doping, in the strong-coupling limit, in favor of d-wave superconductivity. At the particle-hole invariant chemical potential, we find a first-order phase transition from antiferromagnetism (AF) to d-wave superconductivity as a function of the attractive nearest-neighbor interaction, along with a deviation of the density from the half-filled limit. A repulsive extended interaction instead favors charge-density wave (CDW) order at half-filling.

• Efficient qudit based scheme for photonic quantum computing

  Márton Karácsony, László Oroszlány, Zoltan Zimboras

  SciPost Phys. Core 7, 032 (2024) · published 3 June 2024 | Toggle abstract · pdf

  Linear optics is a promising alternative for the realization of quantum computation protocols due to the recent advancements in integrated photonic technology. In this context, usually qubit based quantum circuits are considered, however, photonic systems naturally allow also for d-ary, i.e., qudit based, algorithms. This work investigates qudits defined by the possible photon number states of a single photon in d > 2 optical modes. We demonstrate how to construct locally optimal non-deterministic many-qudit gates using linear optics and photon number resolving detectors, and explore the use of qudit cluster states in the context of a d-ary optimization problem. We find that the qudit cluster states require less optical modes and are encoded by a fewer number of entangled photons than the qubit cluster states with similar computational capabilities. We illustrate the benefit of our qudit scheme by applying it to the k-coloring problem.

• Asymptotic structure of higher dimensional Yang-Mills theory

  Temple He, Prahar Mitra

  SciPost Phys. 16, 142 (2024) · published 30 May 2024 | Toggle abstract · pdf

  Using the covariant phase space formalism, we construct the phase space for non-Abelian gauge theories in (d+2)-dimensional Minkowski spacetime for any d ≥ 2, including the edge modes that symplectically pair to the low energy degrees of freedom of the gauge field. Despite the fact that the symplectic form in odd and even-dimensional spacetimes appear ostensibly different, we demonstrate that both cases can be treated in a unified manner by utilizing the shadow transform. Upon quantization, we recover the algebra of the vacuum sector of the Hilbert space and derive a Ward identity that implies the leading soft gluon theorem in (d+2)-dimensional spacetime.

  1 citation

• Boundary conditions for extremal black holes from 2d gravity

  Stephane Detournay, Thomas Smoes, Raphaela Wutte

  SciPost Phys. 16, 141 (2024) · published 30 May 2024 | Toggle abstract · pdf

  We devise new boundary conditions for the near-horizon geometries of extremal BTZ and Kerr black holes, as well as for the ultra-cold limit of the Kerr-de Sitter black hole. These boundary conditions are obtained as the higher-dimensional uplift of recently proposed boundary conditions in two-dimensional gravity. Their asymptotic symmetries consist in the semi-direct product of a Virasoro and a current algebra, of which we determine the central extensions.

• Disordered $\mathcal{N} = (2, 2)$ supersymmetric field theories

  Chi-Ming Chang, Xiaoyang Shen

  SciPost Phys. 16, 140 (2024) · published 30 May 2024 | Toggle abstract · pdf

  We investigate a large class of $\mathcal{N}=(2,2)$ supersymmetric field theories in two dimensions, which contains the Murugan-Stanford-Witten model, and can be naturally regarded as a disordered generalization of the two-dimensional Landau-Ginzburg models. We analyze the two and four-point functions of chiral superfields, and extract from them the central charge, the operator spectrum, and the chaos exponent in these models. Some of the models exhibit a conformal manifold parameterized by the variances of the random couplings. We compute the Zamolodchikov metrics on the conformal manifold, and demonstrate that the chaos exponent varies nontrivally along the conformal manifolds. Finally, we introduce and perform some preliminary analysis of a disordered generalization of the gauged linear sigma models, and discuss the low energy theories as ensemble averages of Calabi-Yau sigma models over complex structure moduli space.

• Incorporating non-local anyonic statistics into a graph decomposition

  Matthias Mühlhauser, Viktor Kott, Kai Phillip Schmidt

  SciPost Phys. Core 7, 031 (2024) · published 30 May 2024 | Toggle abstract · pdf

  In this work we describe how to systematically implement a full graph decomposition to set up a linked-cluster expansion for the topological phase of Kitaev's toric code in a field. This demands to include the non-local effects mediated by the mutual anyonic statistics of elementary charge and flux excitations. Technically, we describe how to consistently integrate such non-local effects into a hypergraph decomposition for single excitations. The approach is demonstrated for the ground-state energy and the elementary excitation energies of charges and fluxes in the perturbed topological phase.