cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Quantum dynamics of Gaudin magnets
Creators: name: He, Wen-Bin
name: Chesi, Stefano
name: Lin, H. -Q.
name: Guan, Xi-Wen
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Quantum dynamics of many-body systems is a fascinating and significant subject for both theory and experiment. The question of how an isolated many-body system evolves to its steady state after a sudden perturbation or quench still remains challenging. In this paper, using the Bethe ansatz wave function, we study the quantum dynamics of an inhomogeneous Gaudin magnet. We derive explicit analytical expressions for various local dynamic quantities with an arbitrary number of flipped bath spins, such as: the spin distribution function, the spin-spin correlation function, and the Loschmidt echo. We also numerically study the relaxation behavior of these dynamic properties, gaining considerable insight into coherence and entanglement between the central spin and the bath. In particular, we find that the spin-spin correlations relax to their steady value via a nearly logarithmic scaling, whereas the Loschmidt echo shows an exponential relaxation to its steady value. Our results advance the understanding of relaxation dynamics and quantum correlations of long-range interacting models of Gaudin type.
AlphaCAMM, a Micromegas-based camera for high-sensitivity screening of alpha surface contamination
Creators: name: Altenmüller, Konrad
name: Castel, Juan F.
name: Cebrián, Susana
name: Dafni, Theopisti
name: Díez-Ibáñez, David
name: Galán, Javier
name: Galindo, Javier
name: García, Juan Antonio
name: Irastorza, Igor G.
name: Luzón, Gloria
name: Margalejo, Cristina
name: Mirallas, Hector
name: Obis, Luis
name: de Solórzano, Alfonso Ortiz
name: Pérez, Oscar
Publisher: name: arXiv
Year: 2022
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: Surface contamination of $^{222}$Rn progeny from the $^{238}$U natural decay chain is one of the most difficult background contributions to measure in rare event searches experiments. In this work we propose AlphaCAMM, a gaseous chamber read with a segmented Micromegas, for the direct measurement of $^{210}$Pb surface contamination of flat samples. The detection concept exploits the readout capabilities of the Micromegas detectors for the reconstruction of $^{210}$Po alpha tracks to increase the signal-to-background ratio. We report here on the design and realization of a first 26$\times$26 cm$^2$ non-radiopure prototype, with which the detection concept is demonstrated by the use of a new algorithm for the reconstruction of alpha tracks. AlphaCAMM aims for minimum detectable $^{210}$Pb activities of $100$ nBq cm$^{-2}$ and sensitivity upper limits about $60$ nBq cm$^{-2}$ at 95\% of C.L., which requires an intrinsic background level of $5\times10^{-8}$ alphas cm$^{-2}$ s$^{-1}$. We discuss here the prospects to reach these sensitivity goals with a radiopure AlphaCAMM prototype currently under construction.
description: Prepared for submission to JINST
A Review of Mathematical and Computational Methods in Cancer Dynamics
Creators: name: Uthamacumaran, Abicumaran
name: Zenil, Hector
Publisher: name: arXiv
Year: 2022
Subjects: subject: Other Quantitative Biology (q-bio.OT)
subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: Cancers are complex adaptive diseases regulated by the nonlinear feedback systems between genetic instabilities, environmental signals, cellular protein flows, and gene regulatory networks. Understanding the cybernetics of cancer requires the integration of information dynamics across multidimensional spatiotemporal scales, including genetic, transcriptional, metabolic, proteomic, epigenetic, and multi-cellular networks. However, the time-series analysis of these complex networks remains vastly absent in cancer research. With longitudinal screening and time-series analysis of cellular dynamics, universally observed causal patterns pertaining to dynamical systems, may self-organize in the signaling or gene expression state-space of cancer triggering processes. A class of these patterns, strange attractors, may be mathematical biomarkers of cancer progression. The emergence of intracellular chaos and chaotic cell population dynamics remains a new paradigm in systems oncology. As such, chaotic and complex dynamics are discussed as mathematical hallmarks of cancer cell fate dynamics herein. Given the assumption that time-resolved single-cell datasets are made available, a survey of interdisciplinary tools and algorithms from complexity theory, are hereby reviewed to investigate critical phenomena and chaotic dynamics in cancer ecosystems. To conclude, the perspective cultivates an intuition for computational systems oncology in terms of nonlinear dynamics, information theory, inverse problems and complexity. We highlight the limitations we see in the area of statistical machine learning but the opportunity at combining it with the symbolic computational power offered by the mathematical tools explored.
description: 68 pages, 3 figures, 2 tables
Rescuing a Quantum Phase Transition with Quantum Noise
Creators: name: Zhang, Gu
name: Novais, Eduardo
name: Baranger, Harold U.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We show that placing a quantum system in contact with an environment can enhance non-Fermi-liquid correlations, rather than destroy quantum effects as is typical. The system consists of two quantum dots in series with two leads; the highly resistive leads couple charge flow through the dots to the electromagnetic environment, the source of quantum noise. While the charge transport inhibits a quantum phase transition, the quantum noise reduces charge transport and restores the transition. We find a non-Fermi-liquid intermediate fixed point for all strengths of the noise. For strong noise, it is similar to the intermediate fixed point of the two-impurity Kondo model.
description: Published version: shortened, several points clarified, references added. 6 pages + 6 supplementary
Holography without counter terms
Creators: name: Ahn, Byoungjoon
name: Hyun, Seungjoon
name: Kim, Kyung Kiu
name: Park, Sang-A
name: Yi, Sang-Heon
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: By considering the behavior of the reduced action under the scaling transformation, we present a unified derivation of the Smarr-like relation for asymptotically anti-de-Sitter planar black holes. This novel Smarr-like relation leads to useful information in the condensed matter systems through the AdS/CMT correspondence. By using our results, we provide an efficient way to obtain the holographically renormalized on-shell action without the information on the explicit forms of counter terms. We find the complete consistency of our results with those in various models discussed in the recent literatures and obtain new implications.
description: 1+13 pages, plain LaTeX; v2: minor improvements; v3 version to appear in PRD
Numerical analysis of effective models for flux-tunable transmon systems
Creators: name: Lagemann, Hannes
name: Willsch, Dennis
name: Willsch, Madita
name: Jin, Fengping
name: De Raedt, Hans
name: Michielsen, Kristel
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Simulations and analytical calculations that aim to describe flux-tunable transmons are usually based on effective models of the corresponding lumped-element model. However, when a control pulse is applied, in most cases it is not known how much the predictions made with the effective models deviate from the predictions made with the original lumped-element model. In this work we compare the numerical solutions of the time-dependent Schrödinger equation for both the effective and the lumped-element models, for microwave and unimodal control pulses (external fluxes). These control pulses are used to model single-qubit (X) and two-qubit gate (Iswap and Cz) transitions. First, we derive a non-adiabatic effective Hamiltonian for a single flux-tunable transmon and compare the pulse response of this model to the one of the corresponding circuit Hamiltonian. Here we find that both models predict similar outcomes for similar control pulses. Then, we study how different approximations affect single-qubit (X) and two-qubit gate (Iswap and Cz) transitions in two different two-qubit systems. For this purpose we consider three different systems in total: a single flux-tunable transmon and two two-qubit systems. In summary, we find that a series of commonly applied approximations (individually and/or in combination) can change the response of a system substantially, when a control pulse is applied.
Resonant tunneling in disordered borophene nanoribbons with line defects
Creators: name: Hu, Pei-Jia
name: Wang, Si-Xian
name: Chen, Xiao-Feng
name: Liang, Zeng-Ren
name: Fang, Tie-Feng
name: Guo, Ai-Min
name: Xu, Hui
name: Sun, Qing-Feng
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Very recently, borophene has been attracting extensive and ongoing interest as the new wonder material with structural polymorphism and superior attributes, showing that the structural imperfection of line defects (LDs) occurs widely at the interface between $ν_{1/5}$ ($χ_3$) and $ν_{1/6}$ ($β_{12}$) boron sheets. Motivated by these experiments, here we present a theoretical study of electron transport through two-terminal disordered borophene nanoribbons (BNRs) with random distribution of LDs. Our results indicate that LDs could strongly affect the electron transport properties of BNRs. In the absence of LDs, both $ν_{1/5}$ and $ν_{1/6}$ BNRs exhibit metallic behavior, in agreement with experiments. While in the presence of LDs, the overall electron transport ability is dramatically decreased, but some resonant peaks of conductance quantum can be found in the transmission spectrum of any disordered BNR with arbitrary arrangement of LDs. These disordered BNRs exhibit metal-insulator transition by varying nanoribbon width with tunable transmission gap in the insulating regime. Furthermore, the bond currents present fringe patterns and two evolution phenomena of resonant peaks are revealed for disordered BNRs with different widths. These results may help for understanding structure-property relationships and designing LD-based nanodevices.
description: Comments are welcome; 6 pages; 4 figures
A Proof of the Conformal Collider Bounds
Creators: name: Hofman, Diego M.
name: Li, Daliang
name: Meltzer, David
name: Poland, David
name: Rejon-Barrera, Fernando
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this paper, we prove that the "conformal collider bounds" originally proposed by Hofman and Maldacena hold for any unitary parity-preserving conformal field theory (CFT) with a unique stress tensor in spacetime dimensions larger than 2. In particular this implies that the ratio of central charges for a unitary 4d CFT lies in the interval $\frac{31}{18} \geq \frac{a}{c} \geq \frac{1}{3}$. For superconformal theories this is further reduced to $\frac{3}{2} \geq \frac{a}{c} \geq \frac{1}{2}$. The proof relies only on CFT first principles - in particular, bootstrap methods - and thus constitutes the first complete field theory proof of these bounds. We further elaborate on similar bounds for non-conserved currents and relate them to results obtained recently from deep inelastic scattering.
description: 25 pages, 2 figures
Embedding Pontryagins Principle in Neural Networks for Optimal Asteroid Landing
Creators: name:  SERGIO CUEVAS DEL VALLE
name:   PABLO SOLANO-LOPEZ
name:   HODEI URRUTXUA
Publisher: name: Proceedings of the Aerospace Europe Conference - EUCASS - CEAS - 2023
Year: 2023
Subjects: AI
NEURAL NETWORKS
OPTIMAL CONTROL
ASTEROID LANDING

description: This work proposes novel Neural Network (NN) training algorithms and architectures to solve with lowcost general Optimal Control problems: regression of the optimal control policy for a given state trajectory. This is achieved via two novelties: first, a novel cost-effective optimal control solver is used for low-cost data augmentation of optimal state-control trajectories, and then combined with Feedforward and General Regression Neural Networks to solve the so-called direct regression problem. Secondly, Pontryagin\'s Maximum Principle is leveraged to modify physics-informed NN to embed the Hamiltonian structure of Optimal Control within the training algorithm for enhanced robustness and generalized performance.
The isoperimetric problem via direct method in noncompact metric measure spaces with lower Ricci bounds
Creators: name: Antonelli, Gioacchino
name: Nardulli, Stefano
name: Pozzetta, Marco
Publisher: name: arXiv
Year: 2022
Subjects: subject: Differential Geometry (math.DG)
subject: Metric Geometry (math.MG)
subject: FOS: Mathematics
subject: Primary: 49Q20, 49J45, 53A35. Secondary: 53C23

description: We establish a structure theorem for minimizing sequences for the isoperimetric problem on noncompact $\mathsf{RCD}(K,N)$ spaces $(X,\mathsf{d},\mathcal{H}^N)$. Under the sole (necessary) assumption that the measure of unit balls is uniformly bounded away from zero, we prove that the limit of such a sequence is identified by a finite collection of isoperimetric regions possibly contained in pointed Gromov--Hausdorff limits of the ambient space $X$ along diverging sequences of points. The number of such regions is bounded linearly in terms of the measure of the minimizing sequence. The result follows from a new generalized compactness theorem, which identifies the limit of a sequence of sets $E_i\subset X_i$ with uniformly bounded measure and perimeter, where $(X_i,\mathsf{d}_i,\mathcal{H}^N)$ is an arbitrary sequence of $\mathsf{RCD}(K,N)$ spaces. An abstract criterion for a minimizing sequence to converge without losing mass at infinity to an isoperimetric set is also discussed. The latter criterion is new also for smooth Riemannian spaces.
description: arXiv admin note: text overlap with arXiv:2107.07318
Analytical computation of process noise matrix in Kalman filter for fitting curved tracks in magnetic field within dense, thick scatterers
Creators: name: Bhattacharya, Kolahal
name: Banerjee, Sudeshna
name: Mondal, Naba K
Publisher: name: arXiv
Year: 2015
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: In the context of track fitting problems by a Kalman filter, the appropriate functional forms of the elements of the random process noise matrix are derived for tracking through thick layers of dense materials and magnetic field. This work complements the form of the process noise matrix obtained by Mankel[1].
description: Total 27 pages, 14 figures, 2 tables
Demystifying the Vulnerability Propagation and Its Evolution via Dependency Trees in the NPM Ecosystem
Creators: name: Liu, Chengwei
name: Chen, Sen
name: Fan, Lingling
name: Chen, Bihuan
name: Liu, Yang
name: Peng, Xin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Software Engineering (cs.SE)
subject: FOS: Computer and information sciences

description: Third-party libraries with rich functionalities facilitate the fast development of Node.js software, but also bring new security threats that vulnerabilities could be introduced through dependencies. In particular, the threats could be excessively amplified by transitive dependencies. Existing research either considers direct dependencies or reasoning transitive dependencies based on reachability analysis, which neglects the NPM-specific dependency resolution rules, resulting in wrongly resolved dependencies. Consequently, further fine-grained analysis, such as vulnerability propagation and their evolution in dependencies, cannot be carried out precisely at a large scale, as well as deriving ecosystem-wide solutions for vulnerabilities in dependencies. To fill this gap, we propose a knowledge graph-based dependency resolution, which resolves the dependency relations of dependencies as trees (i.e., dependency trees), and investigates the security threats from vulnerabilities in dependency trees at a large scale. We first construct a complete dependency-vulnerability knowledge graph (DVGraph) that captures the whole NPM ecosystem (over 10 million library versions and 60 million well-resolved dependency relations). Based on it, we propose DTResolver to statically and precisely resolve dependency trees, as well as transitive vulnerability propagation paths, by considering the official dependency resolution rules. Based on that, we carry out an ecosystem-wide empirical study on vulnerability propagation and its evolution in dependency trees. Our study unveils lots of useful findings, and we further discuss the lessons learned and solutions for different stakeholders to mitigate the vulnerability impact in NPM. For example, we implement a dependency tree based vulnerability remediation method (DTReme) for NPM packages, and receive much better performance than the official tool (npm audit fix).
Fermi liquid theory applied to a film on an oscillating substrate
Creators: name: Kuorelahti, J. A.
name: Tuorila, J. A.
name: Thuneberg, E. V.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We have studied the transmission of transverse oscillations through a thin Fermi liquid film, using Landau's Fermi liquid theory. Fermi liquid theory describes the dynamics of interacting, degenerate fermion systems, for example non-superfluid, i.e.\ normal state \textsuperscript{3}He at millikelvin temperatures. The response of a Fermi liquid to the transverse oscillations of a planar substrate has previously been calculated for a fluid layer of infinite thickness. We have modified these calculations for application to a film of finite thickness, either with a free surface, or as confined between two parallel substrates. The equations take into account contributions to the acoustic impedance from both the collective transverse zero sound mode, as well as the incoherent single-quasiparticle excitations and are solved using numerical methods.
description: 11 pages, 8 figures. Updated to published version. Changes in presentation, no change in results
Electromagnetic instabilities and plasma turbulence driven by electron-temperature gradient
Creators: name: Adkins, T.
name: Schekochihin, A. A.
name: Ivanov, P. G.
name: Roach, C. M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: Electromagnetic (EM) instabilities and turbulence driven by the electron-temperature gradient are considered in a local slab model of a tokamak-like plasma. The model describes perturbations at scales both larger and smaller than the flux-freezing scale $d_e$, and so captures both electrostatic and EM regimes of turbulence. The well-known electrostatic instabilities -- slab and curvature-mediated ETG -- are recovered, and a new instability is found in the EM regime, called the Thermo-Alfvénic instability (TAI). It exists in both a slab version (sTAI, destabilising kinetic Alfvén waves) and a curvature-mediated version (cTAI), which is a cousin of the (electron-scale) kinetic ballooning mode (KBM). The cTAI turns out to be dominant at the largest scales covered by the model (greater than $d_e$ but smaller than $ρ_i$), its physical mechanism hinging on the fast equalisation of the total temperature along perturbed magnetic field lines (in contrast to KBM, which is pressure balanced). A turbulent cascade theory is then constructed, with two energy-injection scales: $d_e$, where the drivers are slab ETG and sTAI, and a larger (parallel system size dependent) scale, where the driver is cTAI. The latter dominates the turbulent transport if the temperature gradient is greater than a certain critical value, which scales inversely with the electron beta. The resulting heat flux scales more steeply with the temperature gradient than that due to electrostatic ETG turbulence, giving rise to stiffer transport. This can be viewed as a physical argument in favour of near-marginal steady-state in electron-transport-controlled plasmas (e.g., the pedestal). While the model is simplistic, the new physics that is revealed by it should be of interest to those attempting to model the effect of EM turbulence in tokamak-relevant configurations with high beta and large electron temperature gradients.
description: 104 pages, 17 figures
Mean-field quantum dynamics for a mixture of Bose-Einstein condensates
Creators: name: Michelangeli, Alessandro
name: Olgiati, Alessandro
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences
subject: 35Q40, 35Q55, 81Q05, 81V70, 82C10

description: We study the effective time evolution of a large quantum system consisting of a mixture of different species of identical bosons in interaction. If the system is initially prepared so as to exhibit condensation in each component, we prove that condensation persists at later times and we show quantitatively that the many-body Schrödinger dynamics is effectively described by a system of coupled cubic non-linear Schrödinger equations, one for each component.
description: Updated version, published on Anal. Math. Phys. 2016
Quasiconformal mappings on the Grushin plane
Creators: name: Gartland, Chris
name: Jung, Derek
name: Romney, Matthew
Publisher: name: arXiv
Year: 2016
Subjects: subject: Metric Geometry (math.MG)
subject: FOS: Mathematics
subject: 30L05, 53C17

description: We prove that a self-homeomorphism of the Grushin plane is quasisymmetric if and only if it is metrically quasiconformal and if and only if it is geometrically quasiconformal. As the main step in our argument, we show that a quasisymmetric parametrization of the Grushin plane by the Euclidean plane must also be geometrically quasiconformal. We also discuss some aspects of the Euclidean theory of quasiconformal maps, such as absolute continuity on almost every compact curve, not satisfied in the Grushin case.
description: 13 pages, 1 figure, this version has additional section on conformal mappings, also minor corrections and improvements
Sharing Begins at Home
Creators: name: Dempsey, William
name: Foster, Ian
name: Fraser, Scott
name: Kesselman, Carl
Publisher: name: arXiv
Year: 2022
Subjects: subject: Digital Libraries (cs.DL)
subject: FOS: Computer and information sciences

description: The broad sharing of research data is widely viewed as of critical importance for the speed, quality, accessibility, and integrity of science. Despite increasing efforts to encourage data sharing, both the quality of shared data, and the frequency of data reuse, remain stubbornly low. We argue here that a major reason for this unfortunate state of affairs is that the organization of research results in the findable, accessible, interoperable, and reusable (FAIR) form required for reuse is too often deferred to the end of a research project, when preparing publications, by which time essential details are no longer accessible. Thus, we propose an approach to research informatics that applies FAIR principles continuously, from the very inception of a research project, and ubiquitously, to every data asset produced by experiment or computation. We suggest that this seemingly challenging task can be made feasible by the adoption of simple tools, such as lightweight identifiers (to ensure that every data asset is findable), packaging methods (to facilitate understanding of data contents), data access methods, and metadata organization and structuring tools (to support schema development and evolution). We use an example from experimental neuroscience to illustrate how these methods can work in practice.
A stochastic McKean--Vlasov equation for absorbing diffusions on the half-line
Creators: name: Hambly, Ben
name: Ledger, Sean
Publisher: name: arXiv
Year: 2016
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics

description: We study a finite system of diffusions on the half-line, absorbed when they hit zero, with a correlation effect that is controlled by the proportion of the processes that have been absorbed. As the number of processes in the system becomes large, the empirical measure of the population converges to the solution of a non-linear stochastic heat equation with Dirichlet boundary condition. The diffusion coefficients are allowed to have finitely many discontinuities (piecewise Lipschitz) and we prove pathwise uniqueness of solutions to the limiting stochastic PDE. As a corollary we obtain a representation of the limit as the unique solution to a stochastic McKean--Vlasov problem. Our techniques involve energy estimation in the dual of the first Sobolev space, which connects the regularity of solutions to their boundary behaviour, and tightness calculations in the Skorokhod M1 topology defined for distribution-valued processes, which exploits the monotonicity of the loss process $L$. The motivation for this model comes from the analysis of large portfolio credit problems in finance.
description: 60 pages, 2 figures
Axion Monodromy and the Weak Gravity Conjecture
Creators: name: Hebecker, Arthur
name: Rompineve, Fabrizio
name: Westphal, Alexander
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Axions with broken discrete shift symmetry (axion monodromy) have recently played a central role both in the discussion of inflation and the `relaxion' approach to the hierarchy problem. We suggest a very minimalist way to constrain such models by the weak gravity conjecture for domain walls: While the electric side of the conjecture is always satisfied if the cosine-oscillations of the axion potential are sufficiently small, the magnetic side imposes a cutoff, $Λ^3 \sim m f M_{pl}$, independent of the height of these `wiggles'. We compare our approach with the recent related proposal by Ibanez, Montero, Uranga and Valenzuela. We also discuss the non-trivial question which version, if any, of the weak gravity conjecture for domain walls should hold. In particular, we show that string compactifications with branes of different dimensions wrapped on different cycles lead to a `geometric weak gravity conjecture' relating volumes of cycles, norms of corresponding forms and the volume of the compact space. Imposing this `geometric conjecture', e.g.~on the basis of the more widely accepted weak gravity conjecture for particles, provides at least some support for the (electric and magnetic) conjecture for domain walls.
description: 22 pages, 2 figures; v2: references added, typos corrected; v3: published version + minor clarifications on self dual flux in Sec. 3.2
Edwards polaron formation : From one to three dimension
Creators: name: Chakraborty, M.
name: Mohanta, N.
name: Taraphder, A.
name: Min, B. I.
name: Fehske, H.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences
subject: 00A79

description: Employing a self-consistent (optimized) variational diagonalization scheme, we investigate the formation of polaronic quasiparticles in a spinless fermion-boson transport model that couples the movement of charge carriers to fluctuations and correlations of a background medium. The background is parameterized by bosonic degrees of freedom. The variational fermion-boson Hilbert space is constructed to achieve high accuracy in one to three spatial dimensions with modest computational requirements. To characterize the ground-state properties of the Edwards model in the single-particle sector, we present exact numerical results for the polaron band dispersion, quasiparticle weight, Drude weight, mass enhancement, and the particle-boson correlations in a wide parameter regime. In the Edwards model, transport will be quasifree, diffusive or boson-assisted in the weakly fermion-boson coupled, fluctuation-dominated or strongly correlated regimes, respectively. Thereby correlated transport is not only assisted but also limited by the bosonic excitations. As a result, the Drude weight remains finite even in the limit of very small boson frequencies. For a strongly correlated background, closed loops are important, in any dimension, to generate a finite effective particle mass even when the free fermion has an infinite mass.
description: 9 pages 13 figures
Probing surface states with many-body wave packet scattering
Creators: name: Damon, F.
name: Georgeot, B.
name: Guéry-Odelin, D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Pattern Formation and Solitons (nlin.PS)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The scattering of 1D matter wave bright solitons on attractive potentials enables one to populate bound states, a feature impossible with noninteracting wave packets. Compared to noninteracting states, the populated states are renormalized by the attractive interactions between atoms and keep the same topology. This renormalization can even transform a virtual state into a bound state. By switching off adiabatically the interactions, the trapped wave packets converge towards the true noninteracting bound states. Our numerical studies show how such scattering experiments can reveal and characterize the surface states of a periodic structure whose translational invariance has been broken. We provide evidence that the corresponding 3D regime should be accessible with current techniques.
description: 6 pages, 8 figures; published version
CUF-Links: Continuous and Ubiquitous FAIRness Linkages for reproducible research
Creators: name: Foster, Ian
name: Kesselman, Carl
Publisher: name: arXiv
Year: 2022
Subjects: subject: Software Engineering (cs.SE)
subject: Social and Information Networks (cs.SI)
subject: FOS: Computer and information sciences

description: Despite much creative work on methods and tools, reproducibility -- the ability to repeat the computational steps used to obtain a research result -- remains elusive. One reason for these difficulties is that extant tools for capturing research processes do not align well with the rich working practices of scientists. We advocate here for simple mechanisms that can be integrated easily with current work practices to capture basic information about every data product consumed or produced in a project. We argue that by thus extending the scope of findable, accessible, interoperable, and reusable (FAIR) data in both time and space to enable the creation of a continuous chain of continuous and ubiquitous FAIRness linkages (CUF-Links) from inputs to outputs, such mechanisms can provide a strong foundation for documenting the provenance linkages that are essential to reproducible research. We give examples of mechanisms that can achieve these goals, and review how they have been applied in practice.
Non-Hermitian Absorption Spectroscopy
Creators: name: Li, Kai
name: Xu, Yong
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: While non-Hermitian Hamiltonians have been experimentally realized in cold atom systems, it remains an outstanding open question of how to experimentally measure their complex energy spectra in momentum space for a realistic system with boundaries. The existence of non-Hermitian skin effects may make the question even more difficult to address given the fact that energy spectra for a system with open boundaries are dramatically different from those in momentum space; the fact may even lead to the notion that momentum-space band structures are not experimentally accessible for a system with open boundaries. Here, we generalize the widely used radio-frequency spectroscopy to measure both real and imaginary parts of complex energy spectra of a non-Hermitian quantum system for either bosonic or fermionic atoms. By weakly coupling the energy levels of a non-Hermitian system to auxiliary energy levels, we theoretically derive a formula showing that the decay of atoms on the auxiliary energy levels reflects the real and imaginary parts of energy spectra in momentum space. We further prove that measurement outcomes are independent of boundary conditions in the thermodynamic limit, providing strong evidence that the energy spectrum in momentum space is experimentally measurable. We finally apply our non-Hermitian absorption spectroscopy protocol to the Hatano-Nelson model and non-Hermitian Weyl semimetals to demonstrate its feasibility.
description: 30 pages including Supplemental Material, 16 figures
Constraints on the Evolution of the Galaxy Stellar Mass Function I: Role of Star Formation, Mergers and Stellar Stripping
Creators: name: Contini, E.
name: Kang, X.
name: Romeo, A. D.
name: Xia, Q.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We study the connection between the observed star formation rate-stellar mass (SFR-$M_*$) relation and the evolution of the stellar mass function (SMF) by means of a Subhalo Abundance Matching technique coupled to merger trees extracted from a N-body simulation. Our approach, which considers both galaxy mergers and stellar stripping, is to force the model to match the observed SMF at redshift $z>2$, and let it evolve down to the present time according to the observed (SFR-$M_*$) relation. In this study, we use two different sets of SMFs and two SFR-$M_*$ relations: a simple power law and a relation with a mass-dependent slope. Our analysis shows that the evolution of the SMF is more consistent with a SFR-$M_*$ relation with a mass-dependent slope, in agreement with predictions from other models of galaxy evolution and recent observations. In order to fully and realistically describe the evolution of the SMF, both mergers and stellar stripping must be considered, and we find that both have almost equal effects on the evolution of SMF at the massive end. Taking into account the systematic uncertainties in the observed data, the high-mass end of the SMF obtained by considering stellar stripping results in good agreement with recent observational data from the Sloan Digital Sky Survey (SDSS). At $\log M_* < 11.2$, our prediction at z=0.1 is close to \citet{li-white09} data, but the high-mass end ($\log M_* > 11.2$) is in better agreement with \citet{dsouza15} data which account for more massive galaxies.
description: 16 pages, 9 figures. Accepted by ApJ
Lyman-alpha Forests cool Warm Dark Matter
Creators: name: Baur, Julien
name: Palanque-Delabrouille, Nathalie
name: Yèche, Christophe
name: Magneville, Christophe
name: Viel, Matteo
Publisher: name: arXiv
Year: 2015
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: The free-streaming of keV-scale particles impacts structure growth on scales that are probed by the Lyman-alpha forest of distant quasars. Using an unprecedentedly large sample of medium-resolution QSO spectra from the ninth data release of SDSS, along with a state-of-the-art set of hydrodynamical simulations to model the Lyman-alpha forest in the non-linear regime, we issue one of the tightest bounds to date, from Ly-$α$ data alone, on pure dark matter particles : $m_X > 4.09 \: \rm{keV}$ (95% CL) for early decoupled thermal relics such as a hypothetical gravitino, and correspondingly $m_s > 24.4 \: \rm{keV}$ (95% CL) for a non-resonantly produced right-handed neutrino. This limit depends on the value on $n_s$, and Planck measures a higher value of $n_s$ than SDSS-III/BOSS. Our bounds thus change slightly when Ly-$α$ data are combined with CMB data from Planck 2016. The limits shift to $m_X > 2.96 \: \rm{keV}$ (95% CL) and $m_s > 16.0 \: \rm{keV}$ (95% CL). Thanks to SDSS-III data featuring smaller uncertainties and covering a larger redshift range than SDSS-I data, our bounds confirm the most stringent results established by previous works and are further at odds with a purely non-resonantly produced sterile neutrino as dark matter.
description: 25 pages, 8 figures. Accepted in JCAP. Contents presented at the 2015 SDSS-IV collaboration meeting in Madrid, Spain; 2016 eBOSS collaboration meeting at the EPFL (Lausanne), CH; and the 28th Rencontres de Blois (2016)
Charactering instrumental noises and stochastic gravitational wave signals from combined time-delay interferometry
Creators: name: Wang, Gang
name: Li, Bin
name: Xu, Peng
name: Fan, Xilong
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: LISA will detect gravitational waves (GWs) in the milli-Hz frequency band in space. Time-delay interferometry (TDI) is developed to suppress laser frequency noise beneath the acceleration noise and optical metrology noise. To identify stochastic GW signals, it would be required to characterize these noise components entangled in TDI data streams. In this work, we investigate noises characterization by combining the first-generation TDI channels from Michelson and Relay configurations. The Michelson channels are helpful to characterize acceleration noises in the lower frequency band, and the Relay configuration could effectively resolve optical path noises in the higher frequencies. Synergy could be achieved from their combination to determine these instrumental noises. Based on the characterized noises, we further reconstruct the power spectrum of noise in the selected TDI channel. Two cases are performed to characterize the spectrum shape of a stochastic GW signal. For a modeled signal, its parameter(s) could be directly estimated from the TDI data, and its spectrum could be recovered from the inferred values. And for an unexpected signal, its spectrum may be recognized and retrieved from noise-subtracted residual in which its power spectral density surpasses the noise level.
description: 15 pages, 6 figures, accepted for publication in PRD
A possible interpretation of the Higgs mass by the cosmological attractive relaxion
Creators: name: Huang, Fa Peng
name: Cai, Yifu
name: Li, Hong
name: Zhang, Xinmin
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Recently, a novel idea has been proposed to relax the electroweak hierarchy problem through the cosmological inflation and the axion periodic potential. Here, we further assume that only the attractive inflation is needed to explain the light mass of the Higgs boson, where we do not need a specified periodic potential of the axion field. Attractive inflation during the early universe drives the Higgs boson mass from the large value in the early universe to the small value at present, where the Higgs mass is an evolving parameter of the Universe. Thus, the small Higgs mass can technically originate from the cosmological evolution rather than dynamical symmetry or anthropics. Further, we study the possible collider signals or constraints at future lepton collier and the possible constraints from the muon anomalous magnetic moment. A concrete attractive relaxion model is also discussed, which is consistent with the data of Planck 2015.
description: version published in Chinese Physics C
Enhancing dissipative cat-state generation via nonequilibrium pump fields
Creators: name: Zhou, Zheng-Yang
name: Gneiting, Clemens
name: Qin, Wei
name: You, J. Q.
name: Nori, Franco
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Cat states, which were initially proposed to manifest macroscopic superpositions, play an outstanding role in fundamental aspects of quantum dynamics. In addition, they have potential applications in quantum computation and quantum sensing. However, cat states are vulnerable to dissipation, which puts the focus of cat-state generation on higher speed and increased robustness. Dissipative cat-state generation is a common approach based on the nonlinear coupling between a lossy pump field and a half-frequency signal field. In such an approach, the pump field is usually kept in equilibrium, which limits the cat-state generation. We show that the equilibrium requirement can be removed by leveraging a synchronous pump method. In this nonequilibrium regime, the speed of the cat-state generation can be increased by one order of magnitude, and the robustness to single-photon loss can be enhanced. The realization of synchronous pumps is discussed for both time-multiplexed systems and standing modes.
Eddy-current effects on ferromagnetic resonance: Spin wave excitations and microwave screening effects
Creators: name: Flovik, Vegard
name: Pettersen, Bjørn Holst
name: Wahlström, Erik
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We investigate how controlling induced eddy currents in thin film ferromagnet-normal metal (FM/NM) structures can be used to tailor the local microwave (MW) fields in ferromagnetic resonance (FMR) experiments. The MW fields produced by eddy currents will in general have a relative phase shift with respect to the applied MW field which depends on the sample geometry. The induced fields can thus partially compensate the applied MW field, effectively screening the FM in selected parts of the sample. The highly localized fields produced by eddy currents enable the excitation of spin wave modes with non-zero wave vectors, in contrast to the uniform k = 0 mode normally excited in FMR experiments. We find that the orientation of the applied MW field is one of the key parameters controlling the eddy-current effects. The induced currents are maximized when the applied MW field is oriented perpendicular to the sample plane. Increasing the magnitude of the eddy currents results in a stronger induced MW field, enabling a more effective screening of the applied MW field as well as an enhanced excitation of spin wave modes. This investigation underlines that eddy currents can be used to control the magnitude and phase of the local MW fields in thin film structures.
description: Accepted for publication in J. Appl. Phys. 10 pages, 8 figures
Velten, Dieter (Hrsg.): Glauben - Lehren - Erziehung
Creators: name: Stoll, Gerdi
Publisher: name: Jahrbuch für evangelikale Theologie
Year: 2025

description: 1822366755
description: Jahrbuch für evangelikale Theologie, V. 3 (1989): Jahrbuch für evangelikale Theologie, Band 3
Hierarchy of correlations: Application to Green's functions and interacting topological phases
Creators: name: Gómez-León, Álvaro
Publisher: name: arXiv
Year: 2015
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We study the many-body physics of different quantum systems using a hierarchy of correlations, which corresponds to a generalization of the $1/\mathcal{Z}$ hierarchy. The decoupling scheme obtained from this hierarchy is adapted to calculate double-time Green's functions, and due to its non-perturbative nature, we describe quantum phase transition and topological features characteristic of strongly correlated phases. As concrete examples we consider spinless fermions in a dimers chain and in a honeycomb lattice. We present analytical results which are valid for any dimension and can be generalized to different types of interactions (e.g., long range interactions), which allows us to shed light on the effect of quantum correlations in a very systematic way. Furthermore, we show that this approach provides an efficient framework for the calculation of topological invariants in interacting systems.
description: 14 pages,9 figures
Low-Resolution Precoding for Multi-Antenna Downlink Channels and OFDM
Creators: name: Nedelcu, Andrei Stefan
name: Steiner, Fabian
name: Kramer, Gerhard
Publisher: name: arXiv
Year: 2022
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: Downlink precoding is considered for multi-path multi-input single-output channels where the base station uses orthogonal frequency-division multiplexing and low-resolution signaling. A quantized coordinate minimization (QCM) algorithm is proposed and its performance is compared to other precoding algorithms including squared infinity-norm relaxation (SQUID), multi-antenna greedy iterative quantization (MAGIQ), and maximum safety margin precoding. MAGIQ and QCM achieve the highest information rates and QCM has the lowest complexity measured in the number of multiplications. The information rates are computed for pilot-aided channel estimation and data-aided channel estimation. Bit error rates for a 5G low-density parity-check code confirm the information-theoretic calculations. Simulations with imperfect channel knowledge at the transmitter show that the performance of QCM and SQUID degrades in a similar fashion as zero-forcing precoding with high resolution quantizers.
Flat $δ$-vectors and their Ehrhart polynomials
Creators: name: Hibi, Takayuki
name: Tsuchiya, Akiyoshi
Publisher: name: arXiv
Year: 2016
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 52B05, 52B20

description: We call the $δ$-vector of an integral convex polytope of dimension $d$ flat if the $δ$-vector is of the form $(1,0,\ldots,0,a,\ldots,a,0,\ldots,0)$, where $a \geq 1$. In this paper, we give the complete characterization of possible flat $δ$-vectors. Moreover, for an integral convex polytope $\mathcal{P} \subset \mathbb{R}^N$ of dimension $d$, we let $i(\mathcal{P},n)=|n\mathcal{P} \cap \mathbb{Z}^N|$ and $\ i^*(\mathcal{P},n)=|n(\mathcal{P} \setminus \partial \mathcal{P}) \cap \mathbb{Z}^N|.$ By this characterization, we show that for any $d \geq 1$ and for any $k,\ell \geq 0$ with $k+\ell \leq d-1$, there exist integral convex polytopes $\mathcal{P}$ and $\mathcal{Q}$ of dimension $d$ such that (i) For $t=1,\ldots,k$, we have $i(\mathcal{P},t)=i(\mathcal{Q},t),$ (ii) For $t=1,\ldots,\ell$, we have $i^*(\mathcal{P},t)=i^*(\mathcal{Q},t)$ and (iii) $i(\mathcal{P},k+1) \neq i(\mathcal{Q},k+1)$ and $i^*(\mathcal{P},\ell+1)\neq i^*(\mathcal{Q},\ell+1).$
description: 7 pages