cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Loeb Extension and Loeb Equivalence II
Creators: name: Haosui, Duanmu
name: Schrittesser, David
name: Weiss, William
Publisher: name: arXiv
Year: 2021
Subjects: subject: Functional Analysis (math.FA)
subject: Logic (math.LO)
subject: FOS: Mathematics
subject: 28E05 (primary), 03H05

description: The paper answers two open questions that were raised in by Keisler and Sun. The first question asks, if we have two Loeb equivalent spaces $(Ω, \mathcal F, μ)$ and $(Ω, \mathcal G, ν)$, does there exist an internal probability measure $P$ defined on the internal algebra $\mathcal H$ generated from $\mathcal F\cup \mathcal G$ such that $(Ω, \mathcal H, P)$ is Loeb equivalent to $(Ω, \mathcal F, μ)$? The second open problem asks if the $σ$-product of two $σ$-additive probability spaces is Loeb equivalent to the product of the same two $σ$-additive probability spaces. Continuing work in a previous paper, we give a confirmative answer to the first problem when the underlying internal probability spaces are hyperfinite, a partial answer to the first problem for general internal probability spaces, and settle the second question negatively by giving a counter-example. Finally, we show that the continuity sets in the $σ$-algebra of the $σ$-product space are also in the algebra of the product space.
description: 11 pages
Functional Renormalization Group Approach for Signal Detection
Creators: name: Lahoche, Vincent
name: Samary, Dine Ousmane
name: Tamaazousti, Mohamed
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: This review paper uses renormalization group techniques for signal detection in nearly-continuous positive spectra. We highlight universal aspects of the analogue field-theory approach. The first aim is to present an extended self-consistent construction of the analogue effective field-theory framework for data, which can be viewed as a maximum entropy model. In particular and exploiting universality arguments, we justify the $\mathbb{Z}_2$-symmetry of the classical action and we stress the existence of a large-scale (local) regime and of a small-scale (nonlocal) regime. Secondly and related to noise models, we observe the universal relation between phase transition and symmetry breaking in the vicinity of the detection threshold. Finally, we discuss the issue of defining the covariance matrix for tensorial-like data. Based on the cutting graph prescription, we note the superiority of definitions based on complete graphs of large size for data analysis.
description: 101 pages, 41 figures
CDKT-FL: Cross-Device Knowledge Transfer using Proxy Dataset in Federated Learning
Creators: name: Le, Huy Q.
name: Nguyen, Minh N. H.
name: Pandey, Shashi Raj
name: Zhang, Chaoning
name: Hong, Choong Seon
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: In a practical setting, how to enable robust Federated Learning (FL) systems, both in terms of generalization and personalization abilities, is one important research question. It is a challenging issue due to the consequences of non-i.i.d. properties of client's data, often referred to as statistical heterogeneity, and small local data samples from the various data distributions. Therefore, to develop robust generalized global and personalized models, conventional FL methods need to redesign the knowledge aggregation from biased local models while considering huge divergence of learning parameters due to skewed client data. In this work, we demonstrate that the knowledge transfer mechanism achieves these objectives and develop a novel knowledge distillation-based approach to study the extent of knowledge transfer between the global model and local models. Henceforth, our method considers the suitability of transferring the outcome distribution and (or) the embedding vector of representation from trained models during cross-device knowledge transfer using a small proxy dataset in heterogeneous FL. In doing so, we alternatively perform cross-device knowledge transfer following general formulations as 1) global knowledge transfer and 2) on-device knowledge transfer. Through simulations on three federated datasets, we show the proposed method achieves significant speedups and high personalized performance of local models. Furthermore, the proposed approach offers a more stable algorithm than other baselines during the training, with minimal communication data load when exchanging the trained model's outcomes and representation.
description: Accepted to Engineering Applications of Artificial Intelligence (EAAI)
New results on graph matching from degree preserving growth
Creators: name: Erdős, Péter L.
name: Kharel, Shubha R.
name: Mezei, Tamás Róbert
name: Toroczkai, Zoltán
Publisher: name: arXiv
Year: 2022
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: G.2.1; G.2.2
subject: 05C07, 05C70, 05C80, 05C85

description: The recently introduced \emph{Degree Preserving Growth} model (Nature Physics, \DOI{10.1038/s41567-021-01417-7}) uses matchings to insert new vertices of prescribed degrees into the current graph of an ever-growing graph sequence. The process depends both on the size of the largest available matchings, which is our focus here, as well as on the actual choice of the matching.
 First we show that the question whether a graphic degree sequence, extended with a new degree $2δ$ remains graphic is closely related to the available matchings in the realizations of the sequence. Namely we prove that the extension problem is equivalent to the existence of a realization of the original degree sequence with a matching of size $δ$.
 Second we present lower bounds for the \emph{forcible matching number} of degree sequences. This number is the size of the maximum matchings in any realization of the degree sequence. We then study bounds on the size of maximal matchings in \emph{some} realizations of the sequence, known as the \emph{potential matching number}. We also estimate the minimum size of both the maximal and the maximum matchings, as determined by the degree sequence, independently of graphical realizations. Along this line we answer a question raised by Biedl, Demaine \emph{et al.} (\DOI{10.1016/j.disc.2004.05.003}).
description: It is rewritten and with a changed title
Stability in data-driven MPC: an inherent robustness perspective
Creators: name: Berberich, Julian
name: Köhler, Johannes
name: Müller, Matthias A.
name: Allgöwer, Frank
Publisher: name: arXiv
Year: 2022
Subjects: subject: Systems and Control (eess.SY)
subject: Optimization and Control (math.OC)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Mathematics

description: Data-driven model predictive control (DD-MPC) based on Willems' Fundamental Lemma has received much attention in recent years, allowing to control systems directly based on an implicit data-dependent system description. The literature contains many successful practical applications as well as theoretical results on closed-loop stability and robustness. In this paper, we provide a tutorial introduction to DD-MPC for unknown linear time-invariant (LTI) systems with focus on (robust) closed-loop stability. We first address the scenario of noise-free data, for which we present a DD-MPC scheme with terminal equality constraints and derive closed-loop properties. In case of noisy data, we introduce a simple yet powerful approach to analyze robust stability of DD-MPC by combining continuity of DD-MPC w.r.t. noise with inherent robustness of model-based MPC, i.e., robustness of nominal MPC w.r.t. small disturbances. Moreover, we discuss how the presented proof technique allows to show closed-loop stability of a variety of DD-MPC schemes with noisy data, as long as the corresponding model-based MPC is inherently robust.
description: Final version, accepted for presentation at the 61st IEEE Conference on Decision and Control 2022. This version contains the full proof of Theorem IV.1
Shor-Laflamme distributions of graph states and noise robustness of entanglement
Creators: name: Miller, Daniel
name: Loss, Daniel
name: Tavernelli, Ivano
name: Kampermann, Hermann
name: Bruß, Dagmar
name: Wyderka, Nikolai
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The Shor-Laflamme distribution (SLD) of a quantum state is a collection of local unitary invariants that quantify $k$-body correlations. We show that the SLD of graph states can be derived by solving a graph-theoretical problem. In this way, the mean and variance of the SLD are obtained as simple functions of efficiently computable graph properties. Furthermore, this formulation enables us to derive closed expressions of SLDs for some graph state families. For cluster states, we observe that the SLD is very similar to a binomial distribution, and we argue that this property is typical for graph states in general. Finally, we derive an SLD-based entanglement criterion from the purity criterion and apply it to derive meaningful noise thresholds for entanglement. Our new entanglement criterion is easy to use and also applies to the case of higher-dimensional qudits. In the bigger picture, our results foster the understanding both of quantum error-correcting codes, where a closely related notion of Shor-Laflamme distributions plays an important role, and of the geometry of quantum states, where Shor-Laflamme distributions are known as sector length distributions.
description: 22+18 pages, 8+6 figures, minor changes: title and motivation have been updated, appendix F has been removed to shorten the paper
A quantitative and constructive proof of Willems' Fundamental Lemma and its implications
Creators: name: Berberich, Julian
name: Iannelli, Andrea
name: Padoan, Alberto
name: Coulson, Jeremy
name: Dörfler, Florian
name: Allgöwer, Frank
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optimization and Control (math.OC)
subject: Systems and Control (eess.SY)
subject: FOS: Mathematics
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Willems' Fundamental Lemma provides a powerful data-driven parametrization of all trajectories of a controllable linear time-invariant system based on one trajectory with persistently exciting (PE) input. In this paper, we present a novel proof of this result which is inspired by the classical adaptive control literature and differs from existing proofs in multiple aspects. The proof involves a quantitative and directional PE notion, allowing to characterize robust PE properties via singular value bounds, as opposed to binary rank-based PE conditions. Further, the proof is constructive, i.e., we derive an explicit PE lower bound for the generated data. As a contribution of independent interest, we generalize existing PE results from the adaptive control literature and reveal a crucial role of the system's zeros.
description: Final version, accepted for presentation at the American Control Conference (ACC) 2023
Few-to-many-particle crossover of pair excitations in a superfluid
Creators: name: Resare, Fabian
name: Hofmann, Johannes
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Motivated by recent advances in the creation of few-body atomic Fermi gases with attractive interactions, we study theoretically the few-to-many-particle crossover of pair excitations, which for large particle numbers evolve into a mode that describes amplitude fluctuations of the superfluid order parameter (the "Higgs" mode). Our analysis is based on the hypothesis that salient aspects of the excitation spectrum are captured by interactions between time-reversed pair states in a harmonic oscillator potential. Microscopically, this assumption leads to a Richardson-type pairing model, which is integrable and thus allows a systematic quantitative study of the few-to-many-particle crossover with only minor numerical effort. We first establish a parity effect in the ground-state energy, i.e., a spectral convexity in the energy of open-shell configurations compared to their closed-shell neighbors, which is quantified by a so-called Matveev-Larkin parameter discussed for mesoscopic superconductors, which generalizes the pairing gap to mesoscopic ensembles and which behaves quantitatively differently in a few-body and a many-body regime. The crossover point for this quantity is widely tunable as a function of interaction strength. We then compute the excitation spectrum and demonstrate that the pair excitation energy shows a minimum that deepens with increasing particle number and shifts to smaller interaction strengths, consistent with the finite-size precursor of a quantum phase transition to a superfluid state. We extract a critical finite-size scaling exponent that characterizes the decrease of the gap with increasing particle number.
description: 7 pages, 5 figures
Human-Aware Physical Human-Robot Collaborative Transportation and Manipulation with Multiple Aerial Robots
Creators: name: Li, Guanrui
name: Liu, Xinyang
name: Loianno, Giuseppe
Publisher: name: arXiv
Year: 2022
Subjects: subject: Robotics (cs.RO)
subject: FOS: Computer and information sciences

description: Human-robot interaction will play an essential role in various industries and daily tasks, enabling robots to effectively collaborate with humans and reduce their physical workload. Most of the existing approaches for physical human-robot interaction focus on collaboration between a human and a single ground or aerial robot. In recent years, very little progress has been made in this research area when considering multiple aerial robots, which offer increased versatility and mobility. This paper proposes a novel approach for physical human-robot collaborative transportation and manipulation of a cable-suspended payload with multiple aerial robots. The proposed method enables smooth and intuitive interaction between the transported objects and a human worker. In the same time, we consider distance constraints during the operations by exploiting the internal redundancy of the multi-robot transportation system. The key elements of our approach are (a) a collaborative payload external wrench estimator that does not rely on any force sensor; (b) a 6D admittance controller for human-aerial-robot collaborative transportation and manipulation; (c) a human-aware force distribution that exploits the internal system redundancy to guarantee the execution of additional tasks such inter-human-robot separation without affecting the payload trajectory tracking or quality of interaction. We validate the approach through extensive simulation and real-world experiments. These include scenarios where the robot team assists the human in transporting and manipulating a load, or where the human helps the robot team navigate the environment. We experimentally demonstrate for the first time, to the best of our knowledge, that our approach enables a quadrotor team to physically collaborate with a human in manipulating a payload in all 6 DoF in collaborative human-robot transportation and manipulation tasks.
description: Guanrui Li and Xinyang Liu contributed equally to this paper. This paper has been accepted to IEEE Transaction on Robotics (T-RO): https://ieeexplore.ieee.org/document/10758214. Please cite it with the proper format
Diffusion orthogonal polynomials in 3-dimensional domains bounded by developable surfaces
Creators: name: Orevkov, S. Yu.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics

description: The following problem is studied: describe the triplets $(Ω,g,μ)$, $μ=ρ\,dx$, where $g= (g^{ij}(x))$ is the (co)metric associated with the symmetric second order differential operator $L(f) = \frac{1}ρ\sum_{ij} \partial_i (g^{ij} ρ\,\partial_j f)$ defined on a domain $Ω$ of $\mathbb R^n$ and such that there exists an orthonormal basis of $\mathcal L^2(μ)$ made of polynomials which are eigenvectors of $L$, and the basis is compatible with the filtration of the space of polynomials with respect to some weighted degree.
 In a joint paper with D. Bakry and M. Zani this problem was solved in dimension 2 for the usual degree. In the author's subsequent paper this problem was solved in dimension 2 for any weighted degree. In the present paper this problem is solved in dimension 3 for the usual degree under the condition that $\partialΩ$ contains a piece of a tangent developable surface. The proof is based on Plücker-like formulas in the form given by Ragni Piene. All the found solutions are generalized for any dimension.
description: 29 pages
Introduction Of Quantum Entanglement Measure Based On The Expectation Values Of Pauli Operators
Creators: name: Zeheiry, Mahmood
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In this paper, firstly considering that in separable states, the measurement of one particle has no effect on the measurement of the second particle, we show that Alice and Bob can find directions in which the results of their measurements on the spin of the particle are always maximized. In other words, the state of the particle is an eigenstate for the operator that is applied in that direction, so the sum of the spins of two particles can have a maximum value. We will argue that in entangled states, due to the effect of particle measurement results on each other, Alice and Bob cannot find the desired operators. Therefore, in such measurements, the total spin of the particles will always be less than the mentioned maximum. But we ask them to try and measure in directions that will get the most value. Because this value is maximum for separable states and minimum for fully entangled states, and for the rest of the states, it will be proportional to the degree of entanglement between the two maximum and minimum values, we set this parameter as We are calling it the "separability index". Then, based on this index, the measure of entanglement was introduced and extended to states with higher dimensions. In the end, examples of di-qubit states di-qutrit states, and di-qudit states were investigated and the efficiency of the measure was confirmed by the results of the examples. Considering that in this measure, the values of entanglement are calculated based on the expectation values and we can measure the expectation values in the experiment, we hope to be one step closer to the testability of the entanglement value.
Persistence approximation property for $L^p$ operator algebras
Creators: name: Wang, Hang
name: Wang, Yanru
name: Zhang, Jianguo
name: Zhou, Dapeng
Publisher: name: arXiv
Year: 2022
Subjects: subject: Operator Algebras (math.OA)
subject: K-Theory and Homology (math.KT)
subject: FOS: Mathematics
subject: 46L80, 58B34

description: In this paper, we study the persistence approximation property for quantitative $K$-theory of filtered $L^p$ operator algebras. Moreover, we define quantitative assembly maps for $L^p$ operator algebras when $p\in [1,\infty)$. Finally, in the case of $L^{p}$ crossed products and $L^{p}$ Roe algebras, we find sufficient conditions for the persistence approximation property. This allows us to give some applications involving the $L^{p}$ (coarse) Baum-Connes conjecture.
description: 33 pages, to appear in Chinese Ann. Math. Ser. B
Machine Learning Coarse-Grained Potentials of Protein Thermodynamics
Creators: name: Majewski, Maciej
name: Pérez, Adrià
name: Thölke, Philipp
name: Doerr, Stefan
name: Charron, Nicholas E.
name: Giorgino, Toni
name: Husic, Brooke E.
name: Clementi, Cecilia
name: Noé, Frank
name: De Fabritiis, Gianni
Publisher: name: arXiv
Year: 2022
Subjects: subject: Biomolecules (q-bio.BM)
subject: Machine Learning (cs.LG)
subject: FOS: Biological sciences
subject: FOS: Computer and information sciences

description: A generalized understanding of protein dynamics is an unsolved scientific problem, the solution of which is critical to the interpretation of the structure-function relationships that govern essential biological processes. Here, we approach this problem by constructing coarse-grained molecular potentials based on artificial neural networks and grounded in statistical mechanics. For training, we build a unique dataset of unbiased all-atom molecular dynamics simulations of approximately 9 ms for twelve different proteins with multiple secondary structure arrangements. The coarse-grained models are capable of accelerating the dynamics by more than three orders of magnitude while preserving the thermodynamics of the systems. Coarse-grained simulations identify relevant structural states in the ensemble with comparable energetics to the all-atom systems. Furthermore, we show that a single coarse-grained potential can integrate all twelve proteins and can capture experimental structural features of mutated proteins. These results indicate that machine learning coarse-grained potentials could provide a feasible approach to simulate and understand protein dynamics.
Complete bipartite graphs flexible in the plane
Creators: name: Kovalev, M. D.
name: Orevkov, S. Yu.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Algebraic Geometry (math.AG)
subject: Metric Geometry (math.MG)
subject: FOS: Mathematics

description: A complete bipartite graph $K_{3,3}$, considered as a planar linkage with joints at the vertices and with rods as edges, in general admits only motions as a whole, i.e., is inflexible. Two types of its paradoxical mobility were found by Dixon in 1899. Later on, in a series of papers by different authors, the question of flexibility of $K_{m,n}$ was solved for almost all pairs $(m,n)$. In the present paper, we solve it for all complete bipartite graphs in the Euclidean plane as well as in the sphere and in the hyperbolic plane. We give independent self-contained proofs without extensive computations which are almost the same in the Euclidean, hyperbolic and spherical cases.
description: 21 pages, 6 figures. Changes with respect to v1:: 1). The hyperbolic and spherical cases are included. 2). References [3] and [5] are added
Can we discern millilensed gravitational-wave signals from signals produced by precessing binary black holes with ground-based detectors?
Creators: name: Liu, Anna
name: Kim, Kyungmin
Publisher: name: arXiv
Year: 2023
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Millilensed gravitational waves (GWs) can potentially be identified by the interference signatures caused by $\sim\!O(10\textrm{--}100)~\textrm{ms}$ time delays between multiple overlapping lensed signals. However, distinguishing millilensed GWs from GWs generated by precessing binary black-hole mergers can be challenging due to their apparent similar waveform shapes. This morphological similarity may be an obstacle to template-based searches to correctly identifying the origin of observed GWs and poses a fundamental question, can we discern millilensed GW signals from signals produced by precessing binary black holes? In this study, we investigate the feasibility of distinguishing between these GWs by performing a proof-of-principle injection study of simulated millilensed precessing GW signals, within the context of ground-based LIGO-Virgo-KAGRA detector network detections. Our findings indicate that it is possible to differentiate between the two effects by comparing signal-to-noise ratios (SNRs) computed using templates based on different hypotheses for the target signal. We further show from the parameter estimation study that while lensing magnification is sensitive to precession, it is possible to identify millilensing in precessing GW signals with an SNR of 18. The recovery of precession in the presence of lensing is more challenging but improves significantly for signals with an SNR of 40. Nonetheless, neglecting millilensing effects results in biases in the recovered spins, revealing the importance of accounting for these effects in accurate GW signal analysis.
description: 18 pages, 16 figures, 7 tables; published in PRD
State polynomials: positivity, optimization and nonlinear Bell inequalities
Creators: name: Klep, Igor
name: Magron, Victor
name: Volčič, Jurij
name: Wang, Jie
Publisher: name: arXiv
Year: 2023
Subjects: subject: Functional Analysis (math.FA)
subject: Optimization and Control (math.OC)
subject: Quantum Physics (quant-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: This paper introduces state polynomials, i.e., polynomials in noncommuting variables and formal states of their products. A state analog of Artin's solution to Hilbert's 17th problem is proved showing that state polynomials, positive over all matrices and matricial states, are sums of squares with denominators. Somewhat surprisingly, it is also established that a Krivine-Stengle Positivstellensatz fails to hold in the state polynomial setting. Further, archimedean Positivstellensätze in the spirit of Putinar and Helton-McCullough are presented leading to a hierarchy of semidefinite relaxations converging monotonically to the optimum of a state polynomial subject to state constraints. This hierarchy can be seen as a state analog of the Lasserre hierarchy for optimization of polynomials, and the Navascués-Pironio-Acín scheme for optimization of noncommutative polynomials. The motivation behind this theory arises from the study of correlations in quantum networks. Determining the maximal quantum violation of a polynomial Bell inequality for an arbitrary network is reformulated as a state polynomial optimization problem. Several examples of quadratic Bell inequalities in the bipartite and the bilocal tripartite scenario are analyzed. To reduce the size of the constructed SDPs, sparsity, sign symmetry and conditional expectation of the observables' group structure are exploited. To obtain the above-mentioned results, techniques from noncommutative algebra, real algebraic geometry, operator theory, and convex optimization are employed.
Cosmic primordial density fluctuations and Bell inequalities
Creators: name: Dale, Roberto
name: Lapiedra, Ramon
name: Morales-Lladosa, Juan Antonio
Publisher: name: arXiv
Year: 2023
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The temperature measurements, $T$, of the perturbed cosmic microwave background, performed by the cosmic background explorer satellite (COBE), are considered. A dichotomist function, $f = \pm 1$, is defined such that $f =+1$ if $δT > 0$ and $f =-1$ if $δT < 0$, where $δT$ stands for the fluctuation of $T$. Then, it is assumed that behind the appearance of these fluctuations there is local realism. Under this assumption, some specific Clauser-Horne-Shimony-Holt (CHSH) inequalities are proved for these fluctuation temperatures measured by COBE in the different sky directions. The calculation of these inequalities from the actual temperature measurements shows that these inequalities are not violated. This result cannot be anticipated by calculating the commutators of the cosmic density quantum operators. This must be remarked here since, in the case of a system of two entangled spin ${\textstyle{1 \over 2}}$ particles, its CHSH inequalities violation can be inferred from the nonvanishing value of the corresponding spin measurement commutators. The above nonviolation of the observed cosmic CHSH inequalities is compatible with the existence of local realism behind the cosmic measurement results. Nevertheless, assuming again local realism, some new cosmic CHSH inequalities can be derived for the case of the WMAP measurements whose accuracy is better than the one of the above considered COBE measurements. More specifically, in the WMAP case, some significant cross correlations between the temperature and polarization maps are detected, and the new cosmic CHSH inequalities are the ones built with these cross correlations. Now, the occasional violation of these CHSH inequalities would mean the failure of the assumed local realism in accordance with the quantum origin of the primordial temperature and polarization fluctuations in the framework of standard inflation.
description: 15 pages, 4 figures
Wigner State and Process Tomography on Near-Term Quantum Devices
Creators: name: Devra, Amit
name: Glaser, Niklas J.
name: Huber, Dennis
name: Glaser, Steffen J.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present an experimental scanning-based tomography approach for near-term quantum devices. The underlying method has previously been introduced in an ensemble-based NMR setting. Here we provide a tutorial-style explanation along with suitable software tools to guide experimentalists in its adaptation to near-term pure-state quantum devices. The approach is based on a Wigner-type representation of quantum states and operators. These representations provide a rich visualization of quantum operators using shapes assembled from a linear combination of spherical harmonics. These shapes (called droplets in the following) can be experimentally tomographed by measuring the expectation values of rotated axial tensor operators. We present an experimental framework for implementing the scanning-based tomography technique for circuit-based quantum computers and showcase results from IBM quantum experience. We also present a method for estimating the density and process matrices from experimentally tomographed Wigner functions (droplets). This tomography approach can be directly implemented using the Python-based software package \texttt{DROPStomo}.
description: Extended supplemental section on temporal averaging
Robustness of quantum algorithms against coherent control errors
Creators: name: Berberich, Julian
name: Fink, Daniel
name: Holm, Christian
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: Systems and Control (eess.SY)
subject: Optimization and Control (math.OC)
subject: FOS: Physical sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Mathematics

description: Coherent control errors, for which ideal Hamiltonians are perturbed by unknown multiplicative noise terms, are a major obstacle for reliable quantum computing. In this paper, we present a framework for analyzing the robustness of quantum algorithms against coherent control errors using Lipschitz bounds. We derive worst-case fidelity bounds which show that the resilience against coherent control errors is mainly influenced by the norms of the Hamiltonians generating the individual gates. These bounds are explicitly computable even for large circuits, and they can be used to guarantee fault-tolerance via threshold theorems. Moreover, we apply our theoretical framework to derive a novel guideline for robust quantum algorithm design and transpilation, which amounts to reducing the norms of the Hamiltonians. Using the $3$-qubit Quantum Fourier Transform as an example application, we demonstrate that this guideline targets robustness more effectively than existing ones based on circuit depth or gate count. Furthermore, we apply our framework to study the effect of parameter regularization in variational quantum algorithms. The practicality of the theoretical results is demonstrated via implementations in simulation and on a quantum computer.
On temperature of a diamond
Creators: name: Mistry, Ravi
name: Pinzul, Aleksandr
Publisher: name: arXiv
Year: 2023
Subjects: subject: Mathematical Physics (math-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We revisit the definition of the temperature of a causal diamond for the case of a free massless scalar field. The stress is given to the intrinsic, direction-dependent character of this definition. Some important limits are also discussed.
description: 12 pages, 2 figures, matches published version
A random copositive matrix is completely positive with positive probability
Creators: name: Klep, Igor
name: Štrekelj, Tea
name: Zalar, Aljaž
Publisher: name: arXiv
Year: 2023
Subjects: subject: Functional Analysis (math.FA)
subject: Optimization and Control (math.OC)
subject: Quantum Physics (quant-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 13J30, 47L07, 52A40 (Primary), 90C22, 90C27 (Secondary)

description: An $n\times n$ symmetric matrix $A$ is copositive if the quadratic form $x^TAx$ is nonnegative on the nonnegative orthant. The cone of copositive matrices strictly contains the cone of completely positive matrices, i.e., all matrices of the form $BB^T$ for some (possibly rectangular) matrix $B$ with nonnegative entries. The main result, proved using Blekherman's real algebraic geometry inspired techniques and tools of convex geometry, shows that asymptotically, as $n$ goes to infinity, the ratio of volume radii of the two cones is strictly positive. Consequently, the same holds true for the ratio of volume radii of any two cones sandwiched between them, e.g., the cones of positive semidefinite matrices, matrices with nonnegative entries, their intersection and their Minkowski sum.
description: 27 pages. A major rewrite with the addition of applications and detailed discussions on size comparison of cones. The part with the construction of examples will appear in a separate paper
COMCAT: Towards Efficient Compression and Customization of Attention-Based Vision Models
Creators: name: Xiao, Jinqi
name: Yin, Miao
name: Gong, Yu
name: Zang, Xiao
name: Ren, Jian
name: Yuan, Bo
Publisher: name: arXiv
Year: 2023
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Artificial Intelligence (cs.AI)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Attention-based vision models, such as Vision Transformer (ViT) and its variants, have shown promising performance in various computer vision tasks. However, these emerging architectures suffer from large model sizes and high computational costs, calling for efficient model compression solutions. To date, pruning ViTs has been well studied, while other compression strategies that have been widely applied in CNN compression, e.g., model factorization, is little explored in the context of ViT compression. This paper explores an efficient method for compressing vision transformers to enrich the toolset for obtaining compact attention-based vision models. Based on the new insight on the multi-head attention layer, we develop a highly efficient ViT compression solution, which outperforms the state-of-the-art pruning methods. For compressing DeiT-small and DeiT-base models on ImageNet, our proposed approach can achieve 0.45% and 0.76% higher top-1 accuracy even with fewer parameters. Our finding can also be applied to improve the customization efficiency of text-to-image diffusion models, with much faster training (up to $2.6\times$ speedup) and lower extra storage cost (up to $1927.5\times$ reduction) than the existing works.
description: ICML 2023 Poster
Fully Dynamic Submodular Maximization over Matroids
Creators: name: Dütting, Paul
name: Fusco, Federico
name: Lattanzi, Silvio
name: Norouzi-Fard, Ashkan
name: Zadimoghaddam, Morteza
Publisher: name: arXiv
Year: 2023
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: Machine Learning (cs.LG)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: Maximizing monotone submodular functions under a matroid constraint is a classic algorithmic problem with multiple applications in data mining and machine learning. We study this classic problem in the fully dynamic setting, where elements can be both inserted and deleted in real-time. Our main result is a randomized algorithm that maintains an efficient data structure with an $\tilde{O}(k^2)$ amortized update time (in the number of additions and deletions) and yields a $4$-approximate solution, where $k$ is the rank of the matroid.
description: Accepted at ICML 2023
A Domain-Independent Agent Architecture for Adaptive Operation in Evolving Open Worlds
Creators: name: Mohan, Shiwali
name: Piotrowski, Wiktor
name: Stern, Roni
name: Grover, Sachin
name: Kim, Sookyung
name: Le, Jacob
name: De Kleer, Johan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences
subject: I.2.4; I.2.6

description: Model-based reasoning agents are ill-equipped to act in novel situations in which their model of the environment no longer sufficiently represents the world. We propose HYDRA - a framework for designing model-based agents operating in mixed discrete-continuous worlds, that can autonomously detect when the environment has evolved from its canonical setup, understand how it has evolved, and adapt the agents' models to perform effectively. HYDRA is based upon PDDL+, a rich modeling language for planning in mixed, discrete-continuous environments. It augments the planning module with visual reasoning, task selection, and action execution modules for closed-loop interaction with complex environments. HYDRA implements a novel meta-reasoning process that enables the agent to monitor its own behavior from a variety of aspects. The process employs a diverse set of computational methods to maintain expectations about the agent's own behavior in an environment. Divergences from those expectations are useful in detecting when the environment has evolved and identifying opportunities to adapt the underlying models. HYDRA builds upon ideas from diagnosis and repair and uses a heuristics-guided search over model changes such that they become competent in novel conditions. The HYDRA framework has been used to implement novelty-aware agents for three diverse domains - CartPole++ (a higher dimension variant of a classic control problem), Science Birds (an IJCAI competition problem), and PogoStick (a specific problem domain in Minecraft). We report empirical observations from these domains to demonstrate the efficacy of various components in the novelty meta-reasoning process.
Molecular-Scale Visualization of Steric Effects of Ligand Binding to Reconstructed Au(111) Surfaces
Creators: name: Bi, Liya
name: Jamnuch, Sasawat
name: Chen, Amanda
name: Do, Alexandria
name: Balto, Krista P.
name: Wang, Zhe
name: Zhu, Qingyi
name: Wang, Yufei
name: Zhang, Yanning
name: Tao, Andrea R.
name: Pascal, Tod A.
name: Figueroa, Joshua S.
name: Li, Shaowei
Publisher: name: arXiv
Year: 2023
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Direct imaging of single molecules at nanostructured interfaces is a grand challenge, with potential to enable new, precise material architectures and technologies. Of particular interest are the structural morphology and spectroscopic signatures of the adsorbed molecule, where modern probes are only now being developed with the necessary spatial and energetic resolution to provide detailed information at molecule-surface interface. Here, we directly visualize the binding of individual m-terphenyl isocyanide ligands to a reconstructed Au(111) surface through scanning tunneling microscopy (STM) and inelastic electron tunneling spectroscopy (IETS). The site-dependent steric pressure of the various surface features alters the vibrational fingerprints of the m-terphenyl isocyanides, which is characterized with single-molecule precision through joint experimental and theoretical approaches. This study for the first time provides molecular-level insights into the steric-pressure-enabled surface binding selectivity, as well as its effect on the chemical properties of individual surface-binding ligands.
LX-mixers for QAOA: Optimal mixers restricted to subspaces and the stabilizer formalism
Creators: name: Fuchs, Franz G.
name: Bassa, Ruben Pariente
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present a novel formalism to both understand and construct mixers that preserve a given subspace. The method connects and utilizes the stabilizer formalism that is used in error correcting codes. This can be useful in the setting when the quantum approximate optimization algorithm (QAOA), a popular meta-heuristic for solving combinatorial optimization problems, is applied in the setting where the constraints of the problem lead to a feasible subspace that is large but easy to specify. The proposed method gives a systematic way to construct mixers that are resource efficient in the number of controlled not gates and can be understood as a generalization of the well-known X and XY mixers and a relaxation of the Grover mixer: Given a basis of any subspace, a resource efficient mixer can be constructed that preserves the subspace. The numerical examples provided show a dramatic reduction of CX gates when compared to previous results. We call our approach logical X-Mixer or logical X QAOA ($\textbf{LX-QAOA}$), since it can be understood as dividing the subspace into code spaces of stabilizers S and consecutively applying logical rotational X gates associated with these code spaces. Overall, we hope that this new perspective can lead to further insight into the development of quantum algorithms.
Bibliometric Analysis of NIME References and Citations
Creators: name: Fasciani, Stefano
Publisher: name: arXiv
Year: 2023
Subjects: subject: Digital Libraries (cs.DL)
subject: FOS: Computer and information sciences

description: This paper presents a bibliometric analysis that examines the works cited in, as well as those citing, NIME papers; for brevity, we refer to these as `references` and `citations`. Utilizing existing tools, we have computationally extracted data from the NIME proceedings archive and retrieved metadata from an academic database, including details of associated references and citations. From this data, we computed a range of metrics and statistics, which we present in this paper. We offer quantitative insights into NIME as a scholarly publication venue, its connections to other venues, and its relationship with various fields of study and authors. Based on our data interpretations, we provide several recommendations for the community's future. In sharing the software we developed for this study, and the summarized raw data, we enable other NIME researchers to conduct more in-depth investigations and examine specific trends.
Observation of giant two-level systems in a granular superconductor
Creators: name: Kristen, Maximilian
name: Voss, Jan Nicolas
name: Wildermuth, Micha
name: Bilmes, Alexander
name: Lisenfeld, Jürgen
name: Rotzinger, Hannes
name: Ustinov, Alexey V.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Disordered thin films are a common choice of material for superconducting, high impedance circuits used in quantum information or particle detector physics. A wide selection of materials with different levels of granularity are available, but, despite low microwave losses being reported for some, the high degree of disorder always implies the presence of intrinsic defects. Prominently, quantum circuits are prone to interact with two-level systems (TLS), typically originating from solid state defects in the dielectric parts of the circuit, like surface oxides or tunneling barriers. We present an experimental investigation of TLS in granular aluminum thin films under applied mechanical strain and electric fields. The analysis reveals a class of strongly coupled TLS having electric dipole moments up to 30 eA, an order of magnitude larger than dipole moments commonly reported for solid state defects. Notably, these large dipole moments appear more often in films with a higher resistivity. Our observations shed new light on granular superconductors and may have implications for their usage as a quantum circuit material.
description: 14 pages, 9 figures
Causal effect of chemotherapy received dose intensity on survival outcome: a retrospective study in osteosarcoma
Creators: name: Spreafico, Marta
name: Ieva, Francesca
name: Fiocco, Marta
Publisher: name: arXiv
Year: 2023
Subjects: subject: Applications (stat.AP)
subject: FOS: Computer and information sciences

description: This study aims to analyse the effects of reducing Received Dose Intensity (RDI) in chemotherapy treatment for osteosarcoma patients on their survival by using a novel approach. In this scenario, toxic side effects are risk factors for mortality and predictors of future exposure levels, introducing post-assignment confounding.
 Chemotherapy administration data from BO03 and BO06 Randomized Clinical Trials (RCTs) in ostosarcoma are employed to emulate a target trial with three RDI-based exposure strategies: 1) standard, 2) reduced, and 3) highly-reduced RDI. Investigations are conducted between subgroups of patients characterised by poor or good Histological Responses (HRe). Inverse Probability of Treatment Weighting (IPTW) is first used to transform the original population into a pseudo-population which mimics the target randomized cohort. Then, a Marginal Structural Cox Model with effect modification is employed. Conditional Average Treatment Effects (CATEs) are ultimately measured as the difference between the Restricted Mean Survival Time of reduced/highly-reduced RDI strategy and the standard one. Confidence Intervals for CATEs are obtained using a novel IPTW-based bootstrap procedure.
 Significant effect modifications based on HRe were found. Increasing RDI-reductions led to contrasting trends for poor and good responders: the higher the reduction, the better (worsen) was the survival in poor (good) reponders. This study introduces a novel approach to (i) comprehensively address the challenges related to the analysis of chemotherapy data, (ii) mitigate the toxicity-treatment-adjustment bias, and (iii) repurpose existing RCT data for retrospective analyses extending beyond the original trials' intended scopes.
A unified-field theory of genome organization and gene regulation
Creators: name: Negro, Giuseppe
name: Semeraro, Massimiliano
name: Cook, Perter R
name: Marenduzzo, Davide
Publisher: name: arXiv
Year: 2023
Subjects: subject: Biological Physics (physics.bio-ph)
subject: Soft Condensed Matter (cond-mat.soft)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Our aim is to predict how often genic and non-genic promoters fire within a cell. We first review a parsimonious pan-genomic model for genome organization and gene regulation, where transcription rate is determined by proximity in 3D space of promoters to clusters containing appropriate factors and RNA polymerases -- structures variously called transcription factories, hubs, and condensates. This model allows reconciliation of conflicting results indicating that regulatory mammalian networks are both simple (as over-expressing just 4 transcription factors switches cell state) and complex (as genome-wide association studies show phenotypes like cell type are determined by thousands of loci rarely encoding such factors). It also yields simple explanations of how mysterious motifs like quantitative trait loci, enhancers, and silencers work. We then present 3D polymer simulations, and a proximity formula based on our biological model that enables prediction of transcriptional activities of all promoters in three human cell types. This simple fitting-free formula contains just one variable (distance on the genetic map to the nearest active promoter), and we suggest it can be applied to any organism.