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Gaussian boson sampling for binary optimization

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arXiv 2024年

作者： Cazalis, Jean Shah, Tirth Chai, Yahui Kühn, Stefan Jansen, Karl Q.ANT GmbH Handwerkstraße 29 Stuttgart70565 Germany Deutsches Elektronen-Synchrotron DESY Platanenallee 6 Zeuthen15738 Germany Computation-Based Science and Technology Research Center The Cyprus Institute 20 Kavafi Street Nicosia2121 Cyprus

Binary optimization is a fundamental area in computational science, with wide-ranging applications from logistics to cryptography, where the tasks are often formulated as Quadratic or Polynomial Unconstrained Binary Optimization problems (QUBO/PUBO). In this work, we propose to use a parametrized Gaussian Boson Sampler (GBS) with threshold detectors to address such problems. We map general PUBO instance onto a quantum Hamiltonian and optimize the Conditional Value-at-Risk of its energy with respect to the GBS ansatz. In particular, we observe that, when the algorithm reduces to standard Variational Quantum Eigensolver, the cost function is analytical. Therefore, it can be computed efficiently, along with its gradient, for low-degree polynomials using only classical computing resources. Numerical experiments on 3-SAT and Graph Partitioning problems show significant performance gains over random guessing, providing a first proof of concept for our proposed approach. © 2024, CC BY.

关键词： Cost functions

Nucleon axial, tensor, and scalar charges and σ-terms in lattice QCD

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arXiv 2025年

作者： Alexandrou, Constantia Bacchio, Simone Finkenrath, Jacob Iona, Christos Koutsou, Giannis Li, Yan Spanoudes, Gregoris Department of Physics University of Cyprus P.O. Box 20537 Nicosia1678 Cyprus Computation-based Science and Technology Research Center The Cyprus Institute 20 Kavafi Str. Nicosia2121 Cyprus Department of Theoretical Physics European Organization for Nuclear Research CERN Geneva 23CH-1211 Switzerland

We determine the nucleon axial, scalar and tensor charges at the continuum limit by analyzing three Nf = 2+1+1 twisted mass fermion ensembles with all quark masses tuned to approximately their physical values. We include all contributions from valence and sea quarks. We use the Akaike Information Criterion to evaluate systematic errors due to excited states and the continuum extrapolation. For the nucleon isovector axial charge we find guA−d = 1.250(24), in agreement with the experimental value. We compute the axial, tensor and scalar charges for each quark flavor. The axial charge provides crucial information on the intrinsic spin carried by quark in the nucleon and the the latter two provide input for experimental searches of physics beyond the standard model. Moreover, we extract the nucleon σ-terms and find σπN = 41.9(8.1) MeV, for the strange σs = 30(17) MeV and for the charm σc = 82(29) MeV. We also present preliminary results on the isovector quantities using a fourth ensemble at smaller lattice spacing. © 2025, CC BY.

关键词： Tensors

Gluon PDF for the proton using the twisted mass formulation of lattice QCD 39

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Gluon PDF for the proton using the twisted mass formulation ...

39th International Symposium on Lattice Field Theory, LATTICE 2022

作者： Delmar, Joseph Alexandrou, Constantia Cichy, Krzysztof Constantinou, Martha Hadjiyiannakou, Kyriakos Department of Physics Temple University PhiladelphiaPA19122-1801 United States Department of Physics University of Cyprus P.O. Box 20537 Nicosia1678 Cyprus Computation-based Science and Technology Research Center The Cyprus Institute 20 Kavafi Str. Nicosia2121 Cyprus Faculty of Physics Adam Mickiewicz University ul. Uniwersytetu Poznańskiego 2 Poznań61-614 Poland

We present results of the x-dependence of the unpolarized gluon PDF for the proton. We use an Nf = 2 + 1 + 1 ensemble of maximally twisted mass fermions with clover improvement and the Iwasaki improved gluon action. The quark masses are tuned so that the pion mass is 260 MeV. We use a 323 × 64 lattice size with a lattice spacing a = 0.093 fm giving a spatial extent of 3 fm. We employ the pseudo-distribution approach and obtain the light-cone Ioffe time distribution (ITD) combining data for nucleon momentum boosts up to 1.67 GeV and Wilson line lengths, z, up to 0.56 fm. We explore systematic effects such as the dependence on the maximum value of z entering the fits to obtain the gluon PDF. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).

关键词： Germanium compounds

Investigation of pion-nucleon contributions to nucleon matrix elements

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Physical Review D 2024年第9期110卷 094514-094514页

作者： Constantia Alexandrou Giannis Koutsou Yan Li Marcus Petschlies Ferenc Pittler Department of Physics University of Cyprus P.O. Box 20537 1678 Nicosia Cyprus Computation-based Science and Technology Research Center The Cyprus Institute 20 Kavafi Street Nicosia 2121 Cyprus HISKP (Theory) Rheinische Friedrich-Wilhelms-Universität Bonn Nußallee 14-16 53115 Bonn Germany

We investigate contributions of excited states to nucleon matrix elements computed in lattice QCD by employing, in addition to the standard nucleon interpolating operator, pion-nucleon (π−N) operators. We solve a generalized eigenvalue problem (GEVP) to obtain an optimal interpolating operator that minimizes overlap with the π−N states. We derive a variant of the standard application of the GEVP method, which allows for constructing 3-point correlation functions using the optimized interpolating operator without requiring the computationally demanding combination that includes π−N operators in both sink and source. We extract nucleon matrix elements using two twisted mass fermion ensembles, one ensemble generated using pion mass of 346 MeV and one ensemble tuned to reproduce the physical value of the pion mass. Especially, we determine the isoscalar and isovector scalar, pseudoscalar, vector, axial, and tensor matrix elements. We include results obtained using a range of kinematic setups, including momentum in the sink. Our results using this variational approach are compared with previous results obtained using the same ensembles and multistate fits without GEVP improvement. We find that for the physical mass point ensemble, the improvement, in terms of suppression of excited states using this method, is most significant for the case of the matrix elements of the isovector axial and pseudoscalar currents.

关键词： Lattice QCD Particle interactions QCD phenomenology Nucleons Form factors

Nucleon charges and σ-terms in lattice QCD

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arXiv 2024年

作者： Alexandrou, C. Bacchio, S. Finkenrath, J. Iona, C. Koutsou, G. Li, Y. Spanoudes, G. Department of Physics University of Cyprus P.O. Box 20537 Nicosia1678 Cyprus Computation-based Science and Technology Research Center The Cyprus Institute 20 Kavafi Str. Nicosia2121 Cyprus Department of Theoretical Physics European Organization for Nuclear Research CERN Geneva 23CH-1211 Switzerland

We determine the nucleon axial, scalar and tensor charges and the nucleon σ-terms using twisted mass fermions. We employ three ensembles with approximately equal physical volume of about 5.5 fm, three values of the lattice spacing, approximately 0.06 fm, 0.07 fm and 0.08 fm, and with the mass of the degenerate up and down, strange and charm quarks tuned to approximately their physical values. We compute both isovector and isoscalar charges and σ-terms and their flavor decomposition including the disconnected contributions. We use the Akaike Information Criterion to evaluate systematic errors due to excited states and the continuum extrapolation. For the nucleon isovector axial charge we find gAu−d = 1.250(24), in agreement with the experimental value. Moreover, we extract the nucleon σ-terms and find for the light quark content σπN = 41.9(8.1) MeV and for the strange σs = 30(17) MeV. © 2024, CC BY.

关键词： Systematic errors

Reconstructing the Magnetic Field in an Arbitrary Domain via Data-driven Bayesian Methods and Numerical Simulations

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arXiv 2024年

作者： Pavlou, Georgios E. Pavlidou, Vasiliki Harmandaris, Vagelis Institute of Applied and Computational Mathematics Foundation for Research and Technology- Hellas HeraklionGR-71110 Greece Institute of Astrophysics Foundation for Research and Technology- Hellas Vasilika Vouton HeraklionGR-71110 Greece Department of Physics University of Crete HeraklionGR-70013 Greece Department of Mathematics and Applied Mathematics University of Crete HeraklionGR-71409 Greece Computation-Based Science and Technology Research Center The Cyprus Institute Nicosia2121 Cyprus

Inverse problems are prevalent in numerous scientific and engineering disciplines, where the objective is to determine unknown parameters within a physical system using indirect measurements or observations. The inherent challenge lies in deducing the most probable parameter values that align with the collected data. This study introduces an algorithm for reconstructing parameters by addressing an inverse problem formulated through differential equations underpinned by uncertain boundary conditions or variant parameters. We adopt a Bayesian approach for parameter inference, delineating the establishment of prior, likelihood, and posterior distributions, and the subsequent resolution of the maximum a posteriori problem via numerical optimization techniques. The proposed algorithm is applied to the task of magnetic field reconstruction within a conical domain, demonstrating precise recovery of the true parameter values. © 2024, CC BY.

关键词： Differential equations

Symmetry breaking in geometric quantum machine learning in the presence of noise

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arXiv 2024年

作者： Tüysüz, Cenk Chang, Su Yeon Demidik, Maria Jansen, Karl Vallecorsa, Sofia Grossi, Michele Deutsches Elektronen-Synchrotron DESY Zeuthen15738 Germany Institut für Physik Humboldt-Universität zu Berlin Berlin12489 Germany Geneva1211 Switzerland Lausanne1015 Switzerland Computation-Based Science and Technology Research Center The Cyprus Institute Nicosia2121 Cyprus

Geometric quantum machine learning based on equivariant quantum neural networks (EQNN) recently appeared as a promising direction in quantum machine learning. Despite the encouraging progress, the studies are still limited to theory, and the role of hardware noise in EQNN training has never been explored. This work studies the behavior of EQNN models in the presence of noise. We show that certain EQNN models can preserve equivariance under Pauli channels, while this is not possible under the amplitude damping channel. We claim that the symmetry breaking grows linearly in the number of layers and noise strength. We support our claims with numerical data from simulations as well as hardware up to 64 qubits. Furthermore, we provide strategies to enhance the symmetry protection of EQNN models in the presence of noise. Copyright © 2024, The Authors. All rights reserved.

关键词： Neural network models

Towards reliable calculations of thermal rate constants: ring polymer molecular dynamics for the OH + HBr → Br + H2O reaction

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arXiv 2022年

作者： Novikov, Ivan S. Makarov, Edgar M. Suleimanov, Yury V. Shapeev, Alexander V. Skolkovo Institute of Science and Technology Skolkovo Innovation Center Nobel St. 3 Moscow143026 Russia Computation-based Science and Technology Research Center Cyprus Institute 20 Kavafi Street Nicosia2121 Cyprus

We combined Moment Tensor Potential (MTP) and Ring Polymer Molecular Dynamics (RPMD) for calculating the thermal rate constants of the OH + HBr system. We used the active learning (AL) algorithm for constructing a training set during RPMD. We compared the obtained RPMD-AL-MTP rate constants with the ones previously calculated using the quasi-classical trajectories (QCT) and the POTLIB potential energy surface, and with the experimental ones. We demonstrated that the RPMD rate constants were systematically closer to the experimental rate constants than the QCT ones at 200 K, 300 K, and 500 K. © 2022, CC BY-NC-ND.

关键词： Molecular dynamics

Supercurrent Renormalization of N = 1 Supersymmetric Yang-Mills Theory on the lattice 39

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Supercurrent Renormalization of N = 1 Supersymmetric Yang-Mi...

39th International Symposium on Lattice Field Theory, LATTICE 2022

作者： Bergner, G. Costa, M. Panagopoulos, H. Piemonte, S. Soler, I. Spanoudes, G. University of Jena Institute for Theoretical Physics Max-Wien-Platz 1 Jena07743 Germany Department of Physics University of Cyprus 1 Panepistimiou Avenue Aglantzia Nicosia2109 Cyprus Department of Chemical Engineering Cyprus University of Technology 30 Archbishop Kyprianou Str. Limassol3036 Cyprus University of Regensburg Institute for Theoretical Physics Universitätsstr. 31 Regensburg93040 Germany Computation-based Science and Technology Research Center The Cyprus Institute 20 Kavafi Str. Nicosia2121 Cyprus

Supersymmetry on the lattice is explicitly broken by the gluino mass and lattice artifacts. However, it can be restored in the continuum limit by fine tuning the parameters based on the renormalized Ward identities. On the renormalization step not only the mass but also the renormalization of the supercurrent needs to be addressed. Here we present a lattice investigation to obtain the renormalization factors of the supercurrent for N=1 Super-Yang Mills theory in a gauge invariant renormalization scheme. We also provide the conversion factors which are necessary in order to translate our results to the more standard MS scheme. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).

关键词： Supersymmetry