Article
Physics, Multidisciplinary
Barbara Dietz
Summary: Rectangular billiards have mirror symmetries and rotational symmetries, and the eigenstates can be classified based on their transformation properties. The properties of these symmetry-projected eigenstates and symmetry-reduced billiards are analyzed. The spectral properties of the eigenstates of the rectangular billiards follow semi-Poisson statistics, while the complete eigenvalue sequence exhibits Poissonian statistics. Quarter-Poisson statistics are found for the ultrarelativistic billiards corresponding to right triangles with semi-Poisson statistics in the nonrelativistic limit. Scarred wave functions are discovered for the right-triangle billiards.
Article
Physics, Multidisciplinary
Barbara Dietz, Achim Richter
Summary: This study reports on experiments conducted with a flat, superconducting microwave billiard in the shape of a quarter ellipse, which simulates a singular billiard. The experiments investigate the coupling of pointlike scatterers to the microwaves inside the cavity, which is dependent on frequency. The eigenfrequencies of the system were identified, and it was found that their spectral properties vary with frequency.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2022)
Article
Mathematics, Interdisciplinary Applications
P. Garcia
Summary: Inspired by symbolic dynamic of chaotic systems and using machine learning techniques, this work designs a control strategy for complex systems. Unlike traditional modeling methods, the strategy relies on a function that perturbs the system towards a target homoclinic orbit based on its current state. Computer simulations of chaotic systems, including discrete maps, ordinary differential equations, and coupled map networks, illustrate the usefulness of nonlinear control techniques based on machine learning and numerical approach of homoclinic orbits.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Engineering, Mechanical
Tao Wu, Feng An, Xiangyun Gao, Weiqiong Zhong, Juergen Kurths
Summary: Multistep prediction has long been a challenge in many real-world systems. This paper proposes a combination framework called Spatial-Temporal Mapping (STM), which uses Gaussian process regression and delay embedding to address the shortcomings of previous approaches. Experimental results demonstrate that STM outperforms traditional iterative methods in various model and real-world systems, and has potential applications in other practical systems.
NONLINEAR DYNAMICS
(2023)
Article
Physics, Fluids & Plasmas
Felipe Augusto O. Silveira, Sidiney G. Alves, Edson D. Leonel, Denis G. Ladeira
Summary: The study examines the dynamical properties of a charged particle colliding with an oscillating platform in a nonhomogeneous electric field, showcasing regular dynamics or chaotic behavior based on parameter values and initial conditions. Localization and stability of fixed points are carefully analyzed, with investigation into the chaotic sea's average properties using a scaling approach. It is shown that the system belongs to the same universality class as the Fermi-Ulam model.
Article
Physics, Multidisciplinary
Crt Lozej
Summary: Quantum dynamical localization refers to the cessation of wave packet diffusion in momentum space due to quantum interference. It is expected to occur when the typical transport time for momentum diffusion exceeds the Heisenberg time. This paper presents an alternative approach that investigates the transport time through the study of spectral fluctuations of the quantum system, specifically the spectral form factor. The results show a linear relationship between the level repulsion exponents, a measure of dynamical localization, and the transport times obtained from the spectral form factors.
Article
Quantum Science & Technology
Maria Laura Olivera-Atencio, Lucas Lamata, Jesus Casado-Pascual
Summary: Quantum machine learning (QML), which has the potential to revolutionize data processing, faces challenges from environmental noise and dissipation.While traditional efforts seek to combat these hindrances, this perspective proposes harnessing them for potential advantages.Surprisingly, under certain conditions, noise and dissipation can benefit QML.Adapting to open quantum systems holds potential for groundbreaking discoveries that may reshape the future of quantum computing.
ADVANCED QUANTUM TECHNOLOGIES
(2023)
Article
Physics, Multidisciplinary
Brian Flynn, Antonio A. Gentile, Nathan Wiebe, Raffaele Santagati, Anthony Laing
Summary: Accurate models of quantum systems are essential for studying their behavior, but it is challenging to extract these models experimentally. In this study, a novel algorithm called Quantum Model Learning Agent (QMLA) is introduced to reverse engineer Hamiltonian descriptions of target systems. The results demonstrate that QMLA can identify the true model in the majority of instances, even with limited prior information and control over the experimental setup. By exploring different model families, QMLA reliably identifies the family that best describes the system dynamics.
NEW JOURNAL OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
Vladimir A. Yurovsky
Summary: This study investigates the chaotic properties of interacting particles. Even if all particles except one are fixed, the excited states of the moving particle are still chaotic. These states are characterized by the number of principal components (NPC), which increases in a linear manner with the number of strong scatterers. The effect of additional perturbation on the chaotic properties of the system is examined, and the decay of observable fluctuation variance is observed as an indicator of approaching eigenstate thermalization.
PHYSICAL REVIEW LETTERS
(2023)
Article
Mathematics, Applied
G. Gonzalez Acosta, A. Plastino, A. M. Kowalski
Summary: We investigate the nonlinear dynamics of a quartic semiclassical system, which provides a description of the interaction between matter and a field. Our analysis covers both dissipative and conservative scenarios, and focuses on the classical limit of these frameworks. Utilizing a system's invariant associated with the Uncertainty Principle, we determine the dynamics towards the classical regime. We demonstrate the convergence to the classical limit and confirm the fulfillment of the Uncertainty Principle throughout the entire process, including cases with dissipation.
Article
Mathematics, Applied
M. Pnueli, V Rom-Kedar
Summary: Tools for analyzing dynamics of 2 degrees-of-freedom Hamiltonian impact systems are derived, considering integrable, near-integrable, and far-from integrable cases. The results suggest that these tools can classify dynamically different regions in phase space and provide global information on the dynamics for integrable and near-integrable cases.
Article
Quantum Science & Technology
Antonio Macaluso, Matthias Klusch, Stefano Lodi, Claudio Sartori
Summary: This work proposes a universal, efficient framework named Multiple Aggregator Quantum Algorithm (MAQA) that can reproduce the output of various classical supervised machine learning algorithms by utilizing quantum computation advantages. MAQA can be adopted as the quantum counterpart of ensemble algorithms and neural networks. By increasing the depth of the corresponding quantum circuit linearly, MAQA can generate an exponentially large number of different transformations of the input, providing a powerful model for quantum machine learning with computational advantage over classical methods. Additionally, the adoption of MAQA as a hybrid quantum-classical and fault-tolerant quantum algorithm is discussed.
QUANTUM INFORMATION PROCESSING
(2023)
Article
Mathematics, Interdisciplinary Applications
A. C. Tzemos, G. Contopoulos
Summary: The study explores the Bohmian trajectories of a 4-qubit system and finds that the chaotic trajectories are both ergodic and effectively ordered for longer times compared to the 2 and 3-qubit cases. It also shows that the higher the dimensionality of the system, the larger the proportion of chaotic trajectories within the Born distribution, making Born's rule accessible by practically all initial distributions in multiqubit systems.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Multidisciplinary Sciences
Michal Lawniczak, Pavel Kurasov, Szymon Bauch, Malgorzata Bialous, Afshin Akhshani, Leszek Sirko
Summary: The Euler characteristic and the generalized Euler characteristic are important for describing the topological and spectral properties of graphs with mixed vertex conditions. The generalized Euler characteristic can be determined from lowest eigenfrequencies and used to identify the number of Dirichlet vertices, making it a powerful tool for studying physical systems modeled by differential equations on metric graphs.
SCIENTIFIC REPORTS
(2021)
Article
Mechanics
Alberto Racca, Nguyen Anh Khoa Doan, Luca Magri
Summary: This paper proposes a reduced-order model for predicting turbulent flows using a nonlinear decomposition method. By dividing the turbulent flow into spatial and temporal problems, a convolutional autoencoder and an echo state network are used to predict the spatial and temporal evolution respectively, resulting in an autonomous dynamical system. Experimental results demonstrate that this method can accurately predict turbulent flows at different Reynolds numbers and significantly reduce computational time.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Physics, Multidisciplinary
Eric Braaten, Hans-Werner Hammer
Summary: The discovery of the X(3872) resonance being extremely close to the D-*0(D) over bar (0) threshold suggests the presence of approximate nonrelativistic conformal symmetry in neutral charm mesons. This study shows that systems consisting of these mesons with low kinetic energies produced in short-distance reactions can be considered as unparticles, created by operators with definite scaling dimensions in a nonrelativistic conformal field theory.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Yong-Hui Lin, Hans-Werner Hammer, Ulf-G. Meissner
Summary: The study combined analysis of the electromagnetic form factors of nucleon using dispersion theory, providing consistent description of experimental data. The statistical uncertainties of the extracted form factors are estimated using the bootstrap method, while systematic errors are determined from variations of the spectral functions. The results show good agreement with previous analyses and provide insights into future experimental directions.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Fabian Brauneis, Timothy G. Backert, Simeon Mistakidis, Mikhail Lemeshko, Hans-Werner Hammer, Artem G. Volosniev
Summary: In this study, we investigate the ground-state properties of weakly repulsive one-dimensional bosons in the presence of an attractive zero-range impurity potential. We find that there are two cases: all bosons are bound to the impurity or all bosons are in a scattering state, and we derive the critical line that separates these cases in the parameter space. The critical line determines the maximum number of bosons that can be bound by the impurity potential in the thermodynamic limit, forming an artificial atom.
NEW JOURNAL OF PHYSICS
(2022)
Article
Physics, Particles & Fields
Jin-Yi Pang, Martin Ebert, Hans-Werner Hammer, Fabian Mueller, Akaki Rusetsky, Jia-Jun Wu
Summary: The use of effective-range expansion may lead to the generation of spurious sub-threshold poles outside of the convergence range, resulting in inconsistencies in three-body equations. The impact of these spurious poles on the three-body quantization condition in a finite volume is investigated and it is shown that they lead to a peculiar dependence of energy levels on box size. Furthermore, a method for removing these poles, proposed in a recent reference, is demonstrated to be applicable in finite-volume calculations, reproducing the exact structure of energy levels with improved accuracy order by order in the EFT expansion.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Nuclear
Wael Elkamhawy, Hans-Werner Hammer
Summary: We use Halo effective field theory (Halo EFT) to calculate the electromagnetic properties of the deformed one-neutron halo candidate Ne-31. In this framework, Ne-31 is bound by a resonant P-wave interaction between the Ne-30 core and the valence neutron. We adopt a spherical formalism to compute the electromagnetic form factors and the E1-breakup strength distribution of Ne-31 at leading order in Halo EFT, with the associated uncertainties estimated according to our power counting.
JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS
(2023)
Article
Physics, Nuclear
Wael Elkamhawy, Hans-Werner Hammer, Lucas Platter
Summary: We investigate the weak decay of one-neutron halo nuclei into the proton-core continuum using a cluster effective field theory. We calculate both the direct decay into the continuum and the resonant final state interactions between the proton and the core. We discuss in detail the decay of 11Be and compare our results to experimental data. As another example, we predict the branching ratio for β-delayed proton emission in the case of 19C.
Article
Physics, Multidisciplinary
Lukas Rammelmueller, David Huber, Matija Cufar, Joachim Brand, Hans-Werner Hammer, Artem G. Volosniev
Summary: We present a numerical analysis of spin-2 fermions in a one-dimensional harmonic potential in the presence of a magnetic point-like impurity. Ground-state level crossing between sectors with different fermion parities is observed already for a few particles, which indicates a few-body precursor of a quantum phase transition. This picture is further supported by analyzing density-density correlations in momentum space. Finally, we discuss the experimental realization of this system in existing cold-atoms platforms.
Article
Astronomy & Astrophysics
Eric Braaten, Hans-Werner Hammer
Summary: A nonrelativistic unparticle is an excitation created by an operator with a definite scaling dimension in a nonrelativistic field theory with approximate conformal symmetry. The rate of point production for an unparticle depends on its total energy with a power-law exponent determined by its scaling dimension. Using the exact result for the 3-point function of primary operators in a nonrelativistic conformal field theory, we derive the contribution to the point production rate of an unparticle from its decay into another unparticle recoiling against a particle. In the case of a broken conformal symmetry by a large positive scattering length, the exponent of the energy in the point production rate is deduced for the loosely bound two-particle state recoiling against a particle with large relative momentum.
Article
Physics, Nuclear
Simone Velardita, Hector Alvarez-Pol, Thomas Aumann, Yassid Ayyad, Meytal Duer, Hans-Werner Hammer, Liancheng Ji, Alexandre Obertelli, Yelei Sun
Summary: We propose a two-target measurement method to determine the interaction cross section of hypernuclei with a target nucleus. The method allows us to extract the production cross section of a given hypernucleus and its interaction cross section on a specific target from two independent measurements. The matter radius of the hypernucleus can be deduced from the analysis of the interaction cross section.
EUROPEAN PHYSICAL JOURNAL A
(2023)
Article
Physics, Nuclear
Yong-Hui Lin, Hans-Werner Hammer, Ulf-G. Meissner
Summary: Using dispersion theory, the Sigma-to-Lambda transition form factors in electromagnetic interactions are calculated considering the pion electromagnetic form factor, SU(3) chiral perturbation theory, the baryon decuplet, and the pi pi- K coupled-channel effect. The electric form factor is significantly affected by the inclusion of the K channel, while the magnetic form factor is minimally affected. The uncertainties in the three-flavor chiral perturbation theory are estimated using a bootstrap sampling method.
EUROPEAN PHYSICAL JOURNAL A
(2023)
Article
Physics, Nuclear
Matthias Gobel, Bijaya Acharya, Hans-Werner Hammer, Daniel R. Phillips
Summary: In this study, we calculate the E1 breakup of the 2n halo nucleus 11Li using halo effective field theory (Halo EFT) and observe a good agreement with experiment. The neutron-neutron (nn) final-state interactions (FSIs) are found to be the most important contribution to the E1 distribution, while the neutron-core (nc) FSIs slightly shift the peak position to lower energies. Additionally, we investigate the sensitivity of the E1 response to the spin structure of the neutron-9Li interaction.
Article
Physics, Particles & Fields
Yong-Hui Lin, Hans-Werner Hammer, Ulf-G. Meissner
Summary: The electromagnetic form factors of the Lambda hyperon in the time-like region are precisely determined through a dispersion-theoretical analysis of world data. Different scenarios are tested and a good description of the data is obtained in the time-like region. The uncertainties in the form factors are estimated and the magnetic radius is predicted when the electric Lambda radius is taken as a constraint. Various vector meson to baryon coupling constants are also extracted.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Nuclear
S. Dietz, H-W Hammer, S. Konig, A. Schwenk
Summary: Resonances in three-body systems are investigated using pionless effective field theory at leading order. Two complementary methods are employed, including analytically continuing the Faddeev equation to the unphysical sheet and exploring the level structure of three-body states in a finite volume approach. The study focuses on both the three-boson system and the three-neutron system, finding trajectory of Borromean three-body Efimov states turning into resonances for the former and no sign of three-body resonances or virtual states at leading order for the latter.
Article
Physics, Multidisciplinary
Mikhail Maslov, Mikhail Lemeshko, Artem G. Volosniev
Summary: We study the impact of an impurity with a resonance level on a surrounding Fermi gas. Our findings show that the impurity causes changes in its self-energy and the density of the gas, leading to a model-independent deformation of the Fermi gas density. Additionally, the study investigates the time evolution of the density in quench dynamics and the behavior of the system at finite temperatures.
PHYSICAL REVIEW RESEARCH
(2022)
Correction
Physics, Nuclear
P. Capel, D. R. Phillips, H. -W. Hammer