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Automated Quantum Algorithm Synthesis

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arXiv 2025年

作者： Rouillard, Amy Lourens, Matt Petruccione, Francesco Department of Physics Stellenbosch University South Africa School for Data Science and Computational Thinking Stellenbosch University Stellenbosch South Africa Stellenbosch South Africa

We present a computational method to automatically design the n-qubit realisations of quantum algorithms. Our approach leverages a domain-specific language (DSL) that enables the construction of quantum circuits via modular building blocks, making it well-suited for evolutionary search. In this DSL quantum circuits are abstracted beyond the usual gate-sequence description and scale automatically to any problem size. This enables us to learn the algorithm structure rather than a specific unitary implementation. We demonstrate our method by automatically designing three known quantum algorithms—the Quantum Fourier Transform, the Deutsch-Jozsa algorithm, and Grover’s search. Remarkably, we were able to learn the general implementation of each algorithm by considering examples of circuits containing at most 5-qubits. Our method proves robust, as it maintains performance across increasingly large search spaces. Convergence to the relevant algorithm is achieved with high probability and with moderate computational resources. © 2025, CC BY-NC-SA.

关键词： Qubits

Generating Generalised Ground-State Ansatzes from Few-Body Examples

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arXiv 2025年

作者： Lourens, Matt Sinayskiy, Ilya Kriel, Johannes N. Petruccione, Francesco Department of Physics Stellenbosch University Stellenbosch South Africa School of Chemistry and Physics University of KwaZulu-Natal Durban South Africa Stellenbosch South Africa School of Data Science and Computational Thinking Stellenbosch University Stellenbosch South Africa

We introduce a method that generates ground state ansatzes for quantum many-body systems which are both analytically tractable and accurate over wide parameter regimes. Our approach leverages a custom symbolic language to construct tensor network states (TNS) via an evolutionary algorithm. This language provides operations that allow the generated TNS to automatically scale with system size. Consequently, we can evaluate ansatz fitness for small systems, which is computationally efficient, while favouring structures that continue to perform well with increasing system size. This ensures that the ansatz captures robust features of the ground state structure. Remarkably, we find analytically tractable ansatzes with a degree of universality, which encode correlations, capture finite-size effects, accurately predict ground state energies, and offer a good description of critical phenomena. We demonstrate this method on the Lipkin-Meshkov-Glick model (LMG) and the quantum transverse-field Ising model (TFIM), where the same ansatz was independently generated for both. The simple structure of the ansatz allows us to restore broken symmetries and obtain exact expressions for local observables and correlation functions. We also point out an interesting connection between this ansatz and a well-studied sequence in analytical number theory and the one-dimensional classical Ising model. Copyright © 2025, The Authors. All rights reserved.

关键词： Ising model

Adiabatic elimination and Wigner function approach in microscopic derivation of open quantum Brownian motion

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arXiv 2025年

作者： Zungu, Ayanda Sinayskiy, Ilya Petruccione, Francesco School of Chemistry and Physics University of KwaZulu-Natal Durban4001 South Africa Centre for Space Research North-West University Mahikeng2745 South Africa Stellenbosch South Africa School of Data Science and Computational Thinking Department of Physics Stellenbosch University Stellenbosch7604 South Africa

Open quantum Brownian motion (OQBM) represents a new class of quantum Brownian motion where the dynamics of the Brownian particle depend not only on the interactions with a thermal environment but also on the state of the internal degrees of freedom. For an Ohmic bath spectral density with a Lorentz-Drude cutoff frequency at a high-temperature limit, we derive the Born-Markov master equation for the reduced density matrix of an open Brownian particle in a harmonic potential. The resulting master equation is written in phase-space representation using the Wigner function, and due to the separation of associated timescales in the high-damping limit, we perform adiabatic elimination of the momentum variable to obtain OQBM. We numerically solve the derived master equation for the reduced density matrix of the OQBM for Gaussian and non-Gaussian initial distributions. In each case, the OQBM dynamics converge to several Gaussian distributions. To gain physical insight into the studied system, we also plotted the dynamics of the off-diagonal element of the open quantum Brownian particle and found damped coherent oscillations. Finally, we investigated the time-dependent variance in the position of the OQBM walker and observed a transition between ballistic and diffusive behavior. Copyright © 2025, The Authors. All rights reserved.

关键词： Brownian movement

Cosmological Interactions with Phantom Scalar Field: Revisiting Background Phase-Space Analysis with Compactified Variables

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arXiv 2025年

作者： Leon, Genly Shankar, Daya Halder, Amlan Paliathanasis, Andronikos Departamento de Matemáticas Universidad Católica del Norte Avda. Angamos 0610 Casilla 1280 Antofagasta Chile Institute of Systems Science Durban University of Technology Durban4000 South Africa School of Sciences Woxsen University Telangana Hyderabad502345 India School for Data Science and Computational Thinking Department of Mathematical Sciences Stellenbosch University Stellenbosch7602 South Africa

Energy transfer in the dark sector of the universe gives rise to new phenomena of special interest in modern cosmology. When dark energy is modeled as a phantom scalar field, interactions become crucial to avoid Big Rip singularities. In this work, we revisit the phase-space analysis of the field equations by introducing a new set of dimensionless variables distinct from the traditional Hubble normalization approach. These new variables define a compactified phase space for the evolution of physical parameters. We demonstrate that these compactified variables offer fresh insights into the phase-space analysis in gravitational theories, particularly when the dark energy fluid is allowed to possess a negative energy density. Copyright © 2025, The Authors. All rights reserved.

关键词： Phantoms

Noether Symmetries in f (Q) −Cosmology

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arXiv 2025年

作者： Dialektopoulos, Konstantinos F. Leon, Genly Paliathanasis, Andronikos Department of Mathematics and Computer Science Transilvania University of Brasov Eroilor 29 Brasov Romania Departamento de Matemáticas Universidad Católica del Norte Avenida Angamos 0610 Casilla Antofagasta1280 Chile Institute of Systems Science Durban University of Technology Durban4000 South Africa School for Data Science and Computational Thinking Stellenbosch University 44 Banghoek Rd Stellenbosch7600 South Africa

We apply the Noether symmetry analysis in f (Q)-Cosmology to determine invariant functions and conservation laws for the cosmological field equations. For the FLRW background and the four families of connections, it is found that only power-law f (Q) functions admit point Noether symmetries. Finally, exact and analytic solutions are derived using the invariant functions. © 2025, CC BY.

关键词： Astrobiology

Neutrino Decoherence in κ-Minkowski Quantum Spacetime: An Open Quantum Systems Paradigm

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arXiv 2025年

作者： Nandi, Partha Bhattacharyya, Tiasha Majumdar, A.S. Pleasance, Graeme Petruccione, Francesco Department of Physics University of Stellenbosch Stellenbosch7600 South Africa Stellenbosch7604 South Africa Department of Physics Diamond Harbour Women’s University D.H. Road West Bengal Sarisha743368 India S. N. Bose National Centre for Basic Sciences Salt Lake Kolkata700106 India School of Data Science and Computational Thinking University of Stellenbosch Stellenbosch7600 South Africa

We investigate neutrino decoherence within the framework of quantum spacetime, focusing on the κ-Minkowski model. We show that stochastic fluctuations in quantum spacetime induce an energy-dependent decoherence effect, where the decoherence rate scales as E−4. This result aligns with recent IceCube observations, indicating that quantum gravity does not induce significant decoherence for high-energy neutrinos. Additionally, we establish conditions under which quantum spacetime effects could influence relic neutrinos, such as those in the cosmic neutrino background (CνB). Our results shed light on how quantum spacetime fluctuations impact neutrino oscillation physics. Copyright © 2025, The Authors. All rights reserved.

关键词： Neutrons

Metaheuristics for Protein Structure Prediction: Review and Empirical Analysis

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Metaheuristics for Protein Structure Prediction: Review and ...

2024 International Conference on Artificial Intelligence and Mechatronics System, AIMS 2024

作者： Oladejo, Sunday O. School for Data Science and Computational Thinking University of Stellenbosch Stellenbosch South Africa

ISBN: (纸本)9798350350524

Metaheuristics have been employed in solving several optimization and NP-hard problems owing to their ability to avoid local optima entrapment, flexibility and robustness, simplicity, and reasonable computational time. In this work, an empirical analysis is carried out on the application of metaheuristics in solving the protein structure prediction (PSP) problem. The PSP problem entails predicting a three-dimensional (3D) structure of proteins based on the amino acid sequences. This study employs the Ab Initio method, which relies on the thermodynamic properties of the proteins, such as the minimal free energy levels, bond angles, and torsional angles, in determining the protein structure. Five real protein sequences, namely 1CB3, 1BXL, 2H3S, 1TZ4, and 1CRN from the Protein data Bank (PDB), and 11 metaheuristics including DE, GA, PSO, DSO, ACO, and HS were employed in the empirical analysis. Moreover, extensive Monte Carlo simulations were carried out to generate the results of the empirical analysis and these results were statistically tested using the Friedman test. © 2024 IEEE.

关键词： Free energy

Compactification of Anisotropies in Einstein-Scalar-Gauss-Bonnet Cosmology

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arXiv 2025年

作者： Giacomini, Alex Paliathanasis, Andronikos Toporensky, Alexey Instituto de Ciencias Físicas y Matemáticas Universidad Austral de Chile Valdivia Chile Institute of Systems Science Department of Mathematics Faculty of Applied Sciences Durban University of Technology Durban4000 South Africa School for Data Science and Computational Thinking Stellenbosch University 44 Banghoek Rd Stellenbosch7600 South Africa Departamento de Matemáticas Universidad Católica del Norte Avda. Angamos 0610 Casilla Antofagasta1280 Chile South Africa Sternberg Astronomical Institute Lomonosov Moscow State University Moscow119991 Russia

We investigate the evolution of anisotropies in Einstein-Gauss-Bonnet theory with a scalar field coupled to the Gauss-Bonnet term. Specifically, we examine the simplest scenario in which the scalar field lacks a kinetic term, and its kinetic contribution arises from an integration by parts of the Gauss-Bonnet scalar. We consider four- and five-dimensional anisotropic spacetimes, focusing on Bianchi I and extended Bianchi I geometries. Our study reveals that the asymptotic solutions correspond to locally symmetric spacetimes where at least two scale factors exhibit analogous behavior or, alternatively, to isotropic configurations where all scale factors evolve identically. Additionally, we discuss the effects of a cosmological constant, finding that the presence of the cosmological constant does not lead to an isotropic universe. © 2025, CC BY.

关键词： Anisotropy

Equivalence of f(Q) cosmology with quintom-like scenario: the phantom field as effective realization of the non-trivial connection

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arXiv 2025年

作者： Basilakos, Spyros Paliathanasis, Andronikos Saridakis, Emmanuel N. National Observatory of Athens Lofos Nymfon Athens11852 Greece Academy of Athens Research Center for Astronomy and Applied Mathematics Soranou Efesiou 4 Athens11527 Greece School of Sciences European University Cyprus Diogenes Street Engomi Nicosia1516 Cyprus Institute of Systems Science Department of Mathematics Faculty of Applied Sciences Durban University of Technology Durban4000 South Africa School for Data Science and Computational Thinking Stellenbosch University 44 Banghoek Rd Stellenbosch7600 South Africa Departamento de Matemáticas Universidad Católica del Norte Avda. Angamos 0610 Casilla Antofagasta1280 Chile CAS Key Laboratory for Researches in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Anhui Hefei230026 China

We show that f(Q) cosmology with a non-trivial connection, namely the Connection II of the literature, is dynamically equivalent with a quintom-like model. In particular, we show that the scalar field arising from the non-linear f(Q) form, and the scalar field associated to the non-trivial connection, are combined to provide one canonical and one phantom field in the minisuperspace Lagrangian. Hence, the combination of two well-behaved fields appears effectively as a phantom field. This is fundamentally different from the usual approach in phantom and quintom cosmology, in which the phantom field is introduced ad hoc, and thus it may open a new way to handle the phantom fields, namely as effective realizations of the connection-related canonical fields. Copyright © 2025, The Authors. All rights reserved.

关键词： Phantoms