Journal: Journal of Physics A: Mathematical and Theoretical

Abbreviation

J. Phys. A: Math. Theor.

Publisher

IOP Publishing

Journal Volumes

ISSN

1751-8113
1361-6447

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Publications 1 - 10 of 119
  • Stringy symmetries and the higher spin square
    Item type: Journal Article
    Gaberdiel, Matthias R.; Gopakumar, Rajesh (2015)
    Journal of Physics A: Mathematical and Theoretical
  • Meta-conformal invariance and the boundedness of two-point correlation functions
    Item type: Journal Article
    Henkel, Malte; Stoimenov, Stoimen (2016)
    Journal of Physics A: Mathematical and Theoretical
  • A novel approach to reduce derivative costs in variational quantum algorithms
    Item type: Journal Article
    Minuto, Giovanni; Melegari, Dario; Caletti, Simone; et al. (2025)
    Journal of Physics A: Mathematical and Theoretical
    We present a detailed numerical study of an alternative approach, named quantum non-demolition measurement (QNDM) (Solinas et al 2023 Eur. Phys. J. D 77 76), to efficiently estimate the gradients or the Hessians of a quantum observable. This is a key step and a resource-demanding task when we want to minimize the cost function associated with a quantum observable. In our detailed analysis, we account for all the resources needed to implement the QNDM approach with a fixed accuracy and compare them to the current state-of-the-art method (Mari et al 2021 Phys. Rev. A 103 012405; Schuld et al 2019 Phys. Rev. A 99 032331; Cerezo et al 2021 Nat. Rev. Phys. 3 625). We find that the QNDM approach is more efficient, i.e. it needs fewer resources, in evaluating the derivatives of a cost function. These advantages are already clear in small dimensional systems and are likely to increase for practical implementations and more realistic situations. A significant outcome of our study is the implementation of the QNDM method in Python, provided in the supplementary material (Caletti and Minuto 2024 https://github.com/ simonecaletti/qndm-gradient). Given that most variational quantum algorithms (VQA) can be formulated within this framework, our results can have significant implications in quantum optimization algorithms and make the QNDM approach a valuable alternative to implement VQA on near-term quantum computers.
  • Topological defects for the free boson CFT
    Item type: Journal Article
    Fuchs, Jurgen; Gaberdiel, Matthias R.; Runkel, Ingo; et al. (2007)
    Journal of Physics A: Mathematical and Theoretical
  • Motivic coaction and single-valued map of polylogarithms from zeta generators
    Item type: Journal Article
    Frost, Hadleigh; Hidding, Martijn; Kamlesh, Deepak; et al. (2024)
    Journal of Physics A: Mathematical and Theoretical
    We introduce a new Lie-algebraic approach to explicitly construct the motivic coaction and single-valued map of multiple polylogarithms in any number of variables. In both cases, the appearance of multiple zeta values is controlled by conjugating generating series of polylogarithms with Lie-algebra generators associated with odd zeta values. Our reformulation of earlier constructions of coactions and single-valued polylogarithms preserves choices of fibration bases, exposes the correlation between multiple zeta values of different depths and paves the way for generalizations beyond genus zero.
  • Maximally extended sl (2|2) as a quantum double
    Item type: Journal Article
    Beisert, Niklas; de Leeuw, Marius; Hecht, Reimar (2016)
    Journal of Physics A: Mathematical and Theoretical
    We derive the universal R-matrix of the quantum-deformed enveloping algebra of centrally extended sl(∣) 2 2 using Drinfeldʼs quantum double con struction. We are led to enlarging the algebra by additional generators corresponding to an sl(2) automorphism. For this maximally extended algebra we construct a consistent Hopf algebra structure where the extensions exhibit several uncommon features. We determine the corresponding universal R-matrix containing some non-standard functions. Curiously, this Hopf algebra has one extra deformation parameter for which the R-matrix does not factorize into products of exponentials.
  • Minimal model holography
    Item type: Journal Article
    Gaberdiel, Matthias R.; Gopakumar, Rajesh (2013)
    Journal of Physics A: Mathematical and Theoretical
  • From boundary to bulk in logarithmic CFT
    Item type: Journal Article
    Gaberdiel, Matthias R.; Runkel, Ingo (2008)
    Journal of Physics A: Mathematical and Theoretical
  • The SAGEX review on scattering amplitudes
    Item type: Review Article
    Travaglini, Gabriele; Brandhuber, Andreas; McLoughlin, Tristan; et al. (2022)
    Journal of Physics A: Mathematical and Theoretical
    This is an introduction to, and invitation to read, a series of review articles on scattering amplitudes in gauge theory, gravity, and superstring theory. Our aim is to provide an overview of the field, from basic aspects to a selection of current (2022) research and developments.
  • When is a pure state of three qubits determined by its single-particle reduced density matrices?
    Item type: Journal Article
    Sawicki, Adam; Walter, Michael; Kuś, Marek (2013)
    Journal of Physics A: Mathematical and Theoretical
Publications 1 - 10 of 119