cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
OSIRIS-REx Contamination Control Strategy and Implementation
Creators: name: Dworkin, J. P.
name: Adelman, L. A.
name: Ajluni, T.
name: Andronikov, A. V.
name: Aponte, J. C.
name: Bartels, A. E.
name: Beshore, E.
name: Bierhaus, E. B.
name: Brucato, J. R.
name: Bryan, B. H.
name: Burton, A. S.
name: Callahan, M. P.
name: Castro-Wallace, S. L.
name: Clark, B. C.
name: Clemett, S. J.
name: Connolly, H. C.
name: Cutlip, W. E.
name: Daly, S. M.
name: Elliott, V. E.
name: Elsila, J. E.
name: Enos, H. L.
name: Everett, D. F.
name: Franchi, I. A.
name: Glavin, D. P.
name: Graham, H. V.
name: Hendershot, J. E.
name: Harris, J. W.
name: Hill, S. L.
name: Hildebrand, A. R.
name: Jayne, G. O.
name: Jenkens, R. W.
name: Johnson, K. S.
name: Kirsch, J. S.
name: Lauretta, D. S.
name: Lewis, A. S.
name: Loiacono, J. J.
name: Lorentson, C. C.
name: Marshall, J. R.
name: Martin, M. G.
name: Matthias, L. L.
name: McLain, H. L.
name: Messenger, S. R.
name: Mink, R. G.
name: Moore, J. L.
name: Nakamura-Messenger, K.
name: Nuth, J. A.
name: Owens, C. V.
name: Parish, C. L.
name: Perkins, B. D.
name: Pryzby, M. S.
name: Reigle, C. A.
name: Righter, K.
name: Rizk, B.
name: Russell, J. F.
name: Sandford, S. A.
name: Schepis, J. P.
name: Songer, J.
name: Sovinski, M. F.
name: Stahl, S. E.
name: Thomas-Keprta, K.
name: Vellinga, J. M.
name: Walker, M. S.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This article describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS- REx spacecraft sampling hardware was maintained at level 100 A/2 and <180 ng/cm2 of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication among scientists, engineers, managers, and technicians.
description: 75 pages, 28 figures, 2 supplements, accepted for publication in Space Science Reviews
Enhanced-Fidelity Ultrafast Geometric Quantum Computation Using Strong Classical Drives
Creators: name: Chen, Ye-Hong
name: Miranowicz, Adam
name: Chen, Xi
name: Xia, Yan
name: Nori, Franco
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We propose a general approach to implement nonadiabatic geometric single- and two-qubit gates beyond the rotating wave approximation (RWA). This protocol is compatible with most optimal control methods used in previous RWA protocols; thus, it is as robust as (or even more robust than) the RWA protocols. Using counter-rotating effects allows us to apply strong drives. Therefore, we can improve the gate speed by 5--10 times compared to the RWA counterpart for implementing high-fidelity ($\geq 99.99\%$) gates. Such an ultrafast evolution (nanoseconds, even picoseconds) significantly reduces the influence of decoherence (e.g., the qubit dissipation and dephasing). Moreover, because the counter-rotating effects no longer induce gate infidelities (in both the weak and strong driving regimes), we can achieve a higher fidelity compared to the RWA protocols. Therefore, in the presence of decoherence, one can implement ultrafast geometric quantum gates with $\geq 99\%$ fidelities.
description: 13 pages, 8 figures, 3 tables
Oxygen-vacancy driven electron localization and itinerancy in rutile-based TiO$_2$
Creators: name: Lechermann, Frank
name: Heckel, Wolfgang
name: Kristanovski, Oleg
name: Müller, Stefan
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Oxygen-deficient TiO$_2$ in the rutile structure as well as the Ti$_3$O$_5$ Magn{é}li phase is investigated within the charge self-consistent combination of density functional theory (DFT) with dynamical mean-field theory (DMFT). It is shown that an isolated oxygen vacancy (V$_{\rm O}$) in titanium dioxide is not sufficient to metallize the system at low temperatures. In a semiconducting phase, an in-gap state is identified at $\varepsilon_{\rm IG}^{\hfill}\sim -0.75\,$eV\, in excellent agreement with experimental data. Band-like impurity levels, resulting from a threefold V$_{\rm O}$-Ti coordination as well as entangled $(t_{2g},e_g)$ states, become localized due to site-dependent electronic correlations. Charge localization and strong orbital polarization occur in the V$_{\rm O}$-near Ti ions, which details can be modified by a variation of the correlated subspace. At higher oxygen vacancy concentration, a correlated metal is stabilized in the Magn{é}li phase. A V$_{\rm O}$-defect rutile structure of identical stoichiometry shows key differences in the orbital-resolved character and the spectral properties. Charge disproportionation is vital in the oxygen-deficient compounds, but obvious metal-insulator transitions driven or sustained by charge order are not identified.
description: 11 pages, 11 figures
Topologically protected dynamics in three-dimensional nonlinear antisymmetric Lotka-Volterra systems
Creators: name: Umer, Muhammad
name: Gong, Jiangbin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: Studies of topological bands and their associated low-dimensional boundary modes have largely focused on linear systems. This work reports robust dynamical features of three-dimensional (3D) nonlinear systems in connection with intriguing topological bands in 3D. Specifically, for a 3D setting of coupled rock-paper-scissors cycles governed by the antisymmetric Lotka-Volterra equation (ALVE) that is inherently nonlinear, we unveil distinct characteristics and robustness of surface polarized masses and analyze them in connection with the dynamics and topological bands of the linearized Lotka-Volterra (LV) equation. Our analysis indicated that insights learned from Weyl semimetal phases with type-I and type-II Weyl singularities based on a linearized version of the ALVE are still remarkably useful, even though the system dynamics is far beyond the linear regime. This work indicates the relevance and importance of the concept of topological boundary modes in analyzing high-dimensional nonlinear systems and hopes to stimulate another wave of topological studies in nonlinear systems.
description: some figures replotted and a few minor changes to the main text
X-ray Spectroscopic Evidence of Charge Exchange Emission in the Disk of M51
Creators: name: Zhang, Shuinai
name: Wang, Q. Daniel
name: Sun, Wei
name: Long, Min
name: Sun, Jia
name: Ji, Li
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: In the disks of spiral galaxies, diffuse soft X-ray emission is known to be strongly correlated with star-forming regions. However, this emission is not simply from a thermal-equilibrium plasma and its origin remains greatly unclear. In this work, we present an X-ray spectroscopic analysis of the emission from the northern hot spot; a region with enhanced star-formation off the nucleus of M51. Based on the high spectral resolution data from XMM-Newton/RGS observations, we unambiguously detect a high $G$ ratio ($3.2^{+6.9}_{-1.5}$) of the OVII He$α$ triplet. This high $G$ ratio is also spatially confirmed by oxygen emission-line maps from the same data. A physical model consisting of a thermal plasma and its charge exchange (CX) with neutral cool gas gives a good explanation for the $G$ ratio and the entire RGS spectra. This model also gives a satisfactory characterization of the complementary Chandra/ACIS-S data, which enables a direct imaging of the diffuse emission, tracing the hot plasma across the galaxy. The hot plasma has a similar characteristic temperature of ~0.34 keV and an approximately solar metallicity. The CX contributes ~50% to the diffuse emission in the 0.4-1.8 keV band, suggesting an effective hot/cool gas interface area about five times the geometric area of the M51 disk. Therefore, the CX appears to play a major role in the soft X-ray production and may be used as a powerful tool to probe the interface astrophysics, important for studying galactic ecosystems.
description: 13 pages, 6 figures, 2 tables, published in ApJ
Microscopic description of production cross sections including deexcitation effects
Creators: name: Sekizawa, Kazuyuki
Publisher: name: arXiv
Year: 2017
Subjects: subject: Nuclear Theory (nucl-th)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Background: At the forefront of the nuclear science, production of new neutron-rich isotopes is continuously pursued at accelerator laboratories all over the world. To explore the currently-unknown territories in the nuclear chart far away from the stability, reliable theoretical predictions are inevitable. Purpose: To provide a reliable prediction of production cross sections taking into account secondary deexcitation processes, both particle evaporation and fission, a new method called TDHF+GEMINI is proposed, which combines the microscopic time-dependent Hartree-Fock (TDHF) theory with a sophisticated statistical compound-nucleus deexcitation model, GEMINI++. Results: The method is applied for multinucleon transfer processes in low-energy heavy ion reactions. It is shown that the inclusion of secondary deexcitation processes, which are dominated by neutron evaporation in the present systems, substantially improves agreement with the experimental data. The magnitude of the evaporation effects is very similar to the one observed in GRAZING calculations. TDHF+GEMINI provides better description of the absolute value of the cross sections for channels involving transfer of more than one protons, compared with the GRAZING results. However, there remain discrepancies between the measurements and the calculated cross sections, indicating a limit of the theoretical framework that works with a single mean-field potential. Possible causes of the discrepancies are discussed. Conclusions: In order to perfectly reproduce experimental cross sections for multinucleon transfer processes, one should go beyond the standard self-consistent mean-field description. Nevertheless, the proposed method will provide valuable information to optimize production mechanisms of new neutron-rich nuclei through its microscopic, non-empirical predictions. (Shortened due to the word limit)
description: 13 pages, 10 figures, 1 table, v3 - Version accepted for publication in PRC
Analyses of trends and behavioral risk factors in the health status of African immigrants in the United States from 2007 to 2017
Creators: name: Yeboah, Nana K.
Publisher: name: No Publisher Supplied
Year: 2023

description: BACKGROUND: African immigrant population in the United States is rapidly burgeoning yet the status of their health is not well known and understood. Although, limited research has found an inverse association between immigrant health and length of stay, few have focus on African immigrants in the US while considering the heterogeneity of this population. The purpose of this study is to evaluate the association between length of stay and the health status of African immigrants and to develop a model to predict increased health risks. METHOD: A quantitative cross-sectional analysis was conducted on adults in the 2007 to 2017 National Health Interview Survey (NHIS) using multivariate logistic regression. The association between length of stay in the US and the health status of African immigrants (3,782) was examined in this study. Additionally, the difference in the behavioral risk factors between African immigrants diagnosed with the health conditions in this study and those with no health conditions was investigated. SAS OnDemand for Academics and Microsoft Excel were used to analyze the data collected from NHIS data. All the results with p values of less than 0.05 were considered as significant. RESULTS: Descriptive analysis of this study revealed that African immigrants with ≥10 years (52.9%) duration in the US were older (p<0.001), better educated (p<0.001), had more annual income (p<0.001) and had health insurance (p<0.001) compared to those residing in the US for < 10 years (47.1%) but were more likely to be diagnosed with one or more of the health conditions studied on this research. Predicators in this study included sociodemographic characteristics, health insurance coverage and behavioral risk factors. The overall prediction of the study outcome revealed an association between independent and dependent variables (independent variables) as related to length of stay in the US. African immigrants without any diagnosed health conditions smoked less, consumer less alcohol, performed more physical activity and had healthier weight compared to those with diagnoses. CONCLUSION: The findings suggests that length of stay is associated with health status of Africa immigrants in the US. Those residing in the US for ≥ 10 years showed more incidents of the disease conditions. It also suggests that lifestyle changes may also improve the health of African immigrants in the US. This study provides further insight into the health of burgeoning African immigrant population.
POSTER: Diagnosis of COVID-19 through Transfer Learning Techniques on CT Scans: A Comparison of Deep Learning Models
Creators: name: Ashraf, Aeyan
name: Malik, Asad
name: Khan, Zahid
Publisher: name: arXiv
Year: 2022
Subjects: subject: Image and Video Processing (eess.IV)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: The novel coronavirus disease (COVID-19) constitutes a public health emergency globally. It is a deadly disease which has infected more than 230 million people worldwide. Therefore, early and unswerving detection of COVID-19 is necessary. Evidence of this virus is most commonly being tested by RT-PCR test. This test is not 100% reliable as it is known to give false positives and false negatives. Other methods like X-Ray images or CT scans show the detailed imaging of lungs and have been proven more reliable. This paper compares different deep learning models used to detect COVID-19 through transfer learning technique on CT scan dataset. VGG-16 outperforms all the other models achieving an accuracy of 85.33% on the dataset.
Measurement Device Independent Quantum Dialogue
Creators: name: Maitra, Arpita
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Very recently, the experimental demonstration of Quantum Secure Direct Communication (QSDC) with state-of-the-art atomic quantum memory has been reported (Phys. Rev. Lett., 2017). Quantum Dialogue (QD) falls under QSDC where the secrete messages are communicated simultaneously between two legitimate parties. The successful experimental demonstration of QSDC opens up the possibilities for practical implementation of QD protocols. Thus, it is necessary to analyze the practical security issues of QD protocols for future implementation. Since the very first proposal for QD by Nguyen (Phys. Lett. A, 2004) a large number of variants and extensions have been presented till date. However, all of those leak half of the secret bits to the adversary through classical communications of the measurement results. In this direction, motivated by the idea of Lo et al. (Phys. Rev. Lett., 2012), we propose a Measurement Device Independent Quantum Dialogue (MDI-QD) scheme which is resistant to such information leakage as well as side channel attacks. In the proposed protocol, Alice and Bob, two legitimate parties, are allowed to prepare the states only. The states are measured by an untrusted third party (UTP) who may himself behave as an adversary. We show that our protocol is secure under this adversarial model. The current protocol does not require any quantum memory and thus it is inherently robust against memory attacks. Such robustness might not be guaranteed in the QSDC protocol with quantum memory (Phys. Rev. Lett., 2017).
Quantum anomalous Hall effect and electric-field-induced topological phase transition in AB-stacked MoTe${}_2$/WSe${}_2$ moiré heterobilayers
Creators: name: Chang, Yao-Wen
name: Chang, Yia-Chung
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We propose a new mechanism to explain the quantum anomalous Hall (QAH) effect and the electric-field-induced topological phase transition in AB-stacked MoTe${}_2$/WSe${}_2$ moiré heterobilayers at $ν=1$ hole filling. We suggest that the Chern band of the QAH state is generated from an intrinsic band inversion composed of the highest two moiré hole bands with opposite valley numbers and a gap opening induced by two Coulomb-interaction-driven magnetic orders. These magnetic orders, including an in-plane $120^{\circ}$-Néel order and an in-plane ferromagnetic order, interact with moiré bands via corresponding in-plane exchange fields. The Néel order ensures the insulating gap, the ferromagnetic order induces the non-zero Chern number, and both orders contribute to time-reversal symmetry breaking. The Néel order is acquired from the Hartree-Fock exchange interaction, and the formation of ferromagnetic order is attributed to interlayer-exciton condensation and exciton ferromagnetism. The exciton ferromagnetism can be demonstrated by excitonic Bose-Hubbard physics and Berezinskii-Kosterlitz-Thouless transition. In low electric fields, the equilibrium state is a Mott-insulator state. At a certain electric field, a correlated insulating state composed of the hole-occupied band and the exciton condensate becomes a new thermodynamically stable phase, and the topological phase transition occurs as the ferromagnetic order emerges. The consistency between the present theory and experimental observations is discussed. Experimental observations, including the spin-polarized/valley-coherent nature of the QAH state, the absence of charge gap closure at the topological phase transition, the canted spin texture, and the insulator-to-metal transition, are interpreted by the mechanism.
description: 18 pages, 6 figures
Non-Hermitian interaction of a discrete state with a continuum
Creators: name: Longhi, Stefano
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The interaction of a discrete state coupled to a continuum is a longstanding problem of major interest in different areas of quantum and classical physics. In Hermitian models, several dynamical decoupling schemes have been suggested, in which the discrete-continuum interaction can be substantially reduced and even suppressed. In this work we consider a discrete state interacting with a continuum via a time-dependent {\em non-Hermitian} coupling with finite (albeit arbitrarily long) duration, and show rather generally that for a wide class of coupling temporal shapes, in which the real and imaginary parts of the coupling are related each other by a Hilbert transform, the discrete state returns to its initial condition after the interaction with the continuum, while the continuum keeps trace of the interaction. Such a behavior, which does not have any counterpart in Hermitian dynamics, can be referred to as non-Hermitian {\em pseudo} decoupling. Non-Hermitian pseudo decoupling is illustrated by considering a non-Hermitian extension of the Fano-Anderson model in a one-dimensional tight-binding lattice. Scuh a non-Hermitian model can describe, for example, photonic hopping dynamics in a tight-binding chain of optical microrings or resonators, in which non-Hermitian coupling can be realized by fast modulation of the real and imaginary (gain/loss) parts of the refractive index of the edge microring.
description: 19 pages, 6 figures, to appear in International Journal of Modern Physics B
Support Vector Machine classification of strong gravitational lenses
Creators: name: Hartley, P.
name: Flamary, R.
name: Jackson, N.
name: Tagore, A. S.
name: Metcalf, R. B.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The imminent advent of very large-scale optical sky surveys, such as Euclid and LSST, makes it important to find efficient ways of discovering rare objects such as strong gravitational lens systems, where a background object is multiply gravitationally imaged by a foreground mass. As well as finding the lens systems, it is important to reject false positives due to intrinsic structure in galaxies, and much work is in progress with machine learning algorithms such as neural networks in order to achieve both these aims. We present and discuss a Support Vector Machine (SVM) algorithm which makes use of a Gabor filterbank in order to provide learning criteria for separation of lenses and non-lenses, and demonstrate using blind challenges that under certain circumstances it is a particularly efficient algorithm for rejecting false positives. We compare the SVM engine with a large-scale human examination of 100000 simulated lenses in a challenge dataset, and also apply the SVM method to survey images from the Kilo-Degree Survey.
description: Accepted by MNRAS
Splashback Shells of Cold Dark Matter Halos
Creators: name: Mansfield, Philip
name: Kravtsov, Andrey V.
name: Diemer, Benedikt
Publisher: name: arXiv
Year: 2016
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: The density field in the outskirts of dark matter halos is discontinuous due to a caustic formed by matter at its first apocenter after infall. In this paper, we present an algorithm to identify the "splashback shell" formed by these apocenters in individual simulated halos using only a single snapshot of the density field. We implement this algorithm in the code SHELLFISH (SHELL Finding In Spheroidal Halos) and demonstrate that the code identifies splashback shells correctly and measures their properties with an accuracy of $<5\%$ for halos with more than 50,000 particles and mass accretion rates of $Γ_\textrm{DK14}>0.5$. Using SHELLFISH, we present the first estimates for several basic properties of individual splashback shells, such as radius, $R_\textrm{sp}$, mass, and overdensity, and provide fits to the distribution of these quantities as functions of $Γ_\textrm{DK14}$, $ν_\textrm{200m}$, and $z.$ We confirm previous findings that $R_\textrm{sp}$ decreases with increasing $Γ_\textrm{DK14}$, but we show that independent of accretion rate, it also decreases with increasing $ν_\textrm{200m}$. We also study the 3D structures of these shells and find that they generally have non-ellipsoidal oval shapes. We find that splashback radii estimated by SHELLFISH are $20\%-30\%$ larger than those estimated in previous studies from stacked density profiles at high accretion rates. We demonstrate that the latter are biased low due to the contribution of high-mass subhalos to these profiles and show that using the median instead of mean density in each radial bin mitigates the effect of substructure on density profiles and removes the bias.
description: 22 pages, 16 figures, source code available at github.com/phil-mansfield/shellfish
Initial condition for baryogenesis via neutrino oscillation
Creators: name: Asaka, Takehiko
name: Eijima, Shintaro
name: Ishida, Hiroyuki
name: Minogawa, Kosuke
name: Yoshii, Tomoya
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We consider a baryogenesis scenario via the oscillation of right-handed neutrinos with Majorana masses of the order of GeV, which are also responsible for neutrino masses by the seesaw mechanism. We study how the initial condition alters the prediction of the present baryon asymmetry by this mechanism. It is usually assumed that the abundance of right-handed neutrinos is zero after the reheating of the inflationary universe and they are produced in scattering processes by the renomalizable Yukawa interaction. However, the higher-dimensional operator with right-handed neutrinos may provide an additional production which is most effective at the reheating epoch. It is shown that such an initial abundance of right-handed neutrinos can significantly modify the prediction when the strong washout of the asymmetry is absent. This leads to the parameter space of the model for the successful baryogenesis being enlarged.
description: 24 pages, 35 figures, v2; correspond to published version
Disorder-Free Localization
Creators: name: Smith, Adam
name: Knolle, Johannes
name: Kovrizhin, Dmitry L.
name: Moessner, Roderich
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The venerable phenomena of Anderson localization, along with the much more recent many-body localization, both depend crucially on the presence of disorder. The latter enters either in the form of quenched disorder in the parameters of the Hamiltonian, or through a special choice of a disordered initial state. Here we present a model with localization arising in a very simple, completely translationally invariant quantum model, with only local interactions between spins and fermions. By identifying an extensive set of conserved quantities, we show that the system generates purely dynamically its own disorder, which gives rise to localization of fermionic degrees of freedom. Our work gives an answer to a decades old question whether quenched disorder is a necessary condition for localization. It also offers new insights into the physics of many-body localization, lattice gauge theories, and quantum disentangled liquids.
description: 5 pages, 4 figures (+ Supplemental Material of 2 pages, 1 figure)
Spectroscopic evidence of flat bands in breathing kagome semiconductor Nb3I8
Creators: name: Regmi, Sabin
name: Fernando, Tharindu
name: Zhao, Yuzhou
name: Sakhya, Anup Pradhan
name: Dhakal, Gyanendra
name: Elius, Iftakhar Bin
name: Vazquez, Hector
name: Denlinger, Jonathan D
name: Yang, Jihui
name: Chu, Jiun-Haw
name: Xu, Xiaodong
name: Cao, Ting
name: Neupane, Madhab
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Kagome materials have become solid grounds to study the interplay among geometry, topology, correlation, and magnetism. Recently, semiconductors Nb3X8(X = Cl, Br, I) have been predicted to be two-dimensional (2D) magnets and importantly these materials possess breathing kagome geometry. Electronic structure study of these promising materials is still lacking. Here, we report the spectroscopic evidence of at and weakly dispersing bands in breathing-kagome semiconductor Nb3I8 around 500 meV binding energy, which is well supported by our first-principles calculations. These bands originate from the breathing kagome lattice of Niobium atoms and have Nb d character. They are found to be sensitive to polarization of the incident photon beam. Our study provides insight into the electronic structure and at band topology in an exfoliable kagome semiconductor thereby providing an important platform to understand the interaction of geometry and electron correlations in 2D material.
description: 7 pages, 4 figures; supplementary information included
Rocks, Water and Noble Liquids: Unfolding the Flavor Contents of Supernova Neutrinos
Creators: name: Baum, Sebastian
name: Capozzi, Francesco
name: Horiuchi, Shunsaku
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: Measuring core-collapse supernova neutrinos, both from individual supernovae within the Milky Way and from past core collapses throughout the Universe (the diffuse supernova neutrino background, or DSNB), is one of the main goals of current and next generation neutrino experiments. Detecting the heavy-lepton flavor (muon and tau types, collectively $ν_x$) component of the flux is particularly challenging due to small statistics and large backgrounds. While the next galactic neutrino burst will be observed in a plethora of neutrino channels, allowing to measure a small number of $ν_x$ events, only upper limits are anticipated for the diffuse $ν_x$ flux even after decades of data taking with conventional detectors. However, paleo-detectors could measure the time-integrated flux of neutrinos from galactic core-collapse supernovae via flavor-blind neutral current interactions. In this work, we show how combining a measurement of the average galactic core-collapse supernova flux with paleo detectors and measurements of the DSNB electron-type neutrino fluxes with the next-generation water Cherenkov detector Hyper-Kamiokande and the liquid noble gas detector DUNE will allow to determine the mean supernova $ν_x$ flux parameters with precision of order ten percent.
description: 18 pages, 5 figures
Randomized Benchmarking Beyond Groups
Creators: name: Chen, Jianxin
name: Ding, Dawei
name: Huang, Cupjin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Randomized benchmarking (RB) is the gold standard for experimentally evaluating the quality of quantum operations. The current framework for RB is centered on groups and their representations, but this can be problematic. For example, Clifford circuits need up to $O(n^2)$ gates, and thus Clifford RB cannot scale to larger devices. Attempts to remedy this include new schemes such as linear cross-entropy benchmarking (XEB), cycle benchmarking, and non-uniform RB, but they do not fall within the group-based RB framework. In this work, we formulate the \emph{universal randomized benchmarking (URB) framework} which does away with the group structure and also replaces the recovery gate plus measurement component with a general ``post-processing'' POVM. Not only does this framework cover most of the existing benchmarking schemes, but it also gives the language for and helps inspire the formulation of new schemes. We specifically consider a class of URB schemes called \emph{twirling schemes}. For twirling schemes, the post-processing POVM approximately factorizes into an intermediate channel, inverting maps, and a final measurement. This leads us to study the twirling map corresponding to the gate ensemble specified by the scheme. We prove that if this twirling map is strictly within unit distance of the Haar twirling map in induced diamond norm, the probability of measurement as a function of gate length is a single exponential decay up to small error terms. The core technical tool we use is the matrix perturbation theory of linear operators on quantum channels.
description: 36 pages
Strong stellar-driven outflows shape the evolution of galaxies at cosmic dawn
Creators: name: Fontanot, Fabio
name: Hirschmann, Michaela
name: De Lucia, Gabriella
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We study galaxy mass assembly and cosmic star formation rate (SFR) at high-redshift (z$\gt$4), by comparing data from multiwavelength surveys with predictions from the GAlaxy Evolution and Assembly (GAEA) model. GAEA implements a stellar feedback scheme partially based on cosmological hydrodynamical simulations, that features strong stellar driven outflows and mass-dependent timescale for the re-accretion of ejected gas. In previous work, we have shown that this scheme is able to correctly reproduce the evolution of the galaxy stellar mass function (GSMF) up to $z\sim3$. We contrast model predictions with both rest-frame Ultra-Violet (UV) and optical luminosity functions (LF), which are mostly sensible to the SFR and stellar mass, respectively. We show that GAEA is able to reproduce the shape and redshift evolution of both sets of LFs. We study the impact of dust on the predicted LFs and we find that the required level of dust attenuation is in qualitative agreement with recent estimates based on the UV continuum slope. The consistency between data and model predictions holds for the redshift evolution of the physical quantities well beyond the redshift range considered for the calibration of the original model. In particular, we show that GAEA is able to recover the evolution of the GSMF up to z$\sim$7 and the cosmic SFR density up to z$\sim$10.
description: 6 pages, 2 figures, accepted on ApJ Letters
Constraining the multi-scale dark-matter distribution in CASSOWARY 31 with strong gravitational lensing and stellar dynamics
Creators: name: Wang, H.
name: Cañameras, R.
name: Caminha, G. B.
name: Suyu, S. H.
name: Yıldırım, A.
name: Chirivì, G.
name: Christensen, L.
name: Grillo, C.
name: Schuldt, S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We study the inner structure of the group-scale lens CASSOWARY 31 (CSWA 31) by adopting both strong lensing and dynamical modeling. CSWA 31 is a peculiar lens system. The brightest group galaxy (BGG) is an ultra-massive elliptical galaxy at z = 0.683 with a weighted mean velocity dispersion of $σ= 432 \pm 31$ km s$^{-1}$. It is surrounded by group members and several lensed arcs probing up to ~150 kpc in projection. Our results significantly improve previous analyses of CSWA 31 thanks to the new HST imaging and MUSE integral-field spectroscopy. From the secure identification of five sets of multiple images and measurements of the spatially-resolved stellar kinematics of the BGG, we conduct a detailed analysis of the multi-scale mass distribution using various modeling approaches, both in the single and multiple lens-plane scenarios. Our best-fit mass models reproduce the positions of multiple images and provide robust reconstructions for two background galaxies at z = 1.4869 and z = 2.763. The relative contributions from the BGG and group-scale halo are remarkably consistent in our three reference models, demonstrating the self-consistency between strong lensing analyses based on image position and extended image modeling. We find that the ultra-massive BGG dominates the projected total mass profiles within 20 kpc, while the group-scale halo dominates at larger radii. The total projected mass enclosed within $R_{eff}$ = 27.2 kpc is $1.10_{-0.04}^{+0.02} \times 10^{13}$ M$_\odot$. We find that CSWA 31 is a peculiar fossil group, strongly dark-matter dominated towards the central region, and with a projected total mass profile similar to higher-mass cluster-scale halos. The total mass-density slope within the effective radius is shallower than isothermal, consistent with previous analyses of early-type galaxies in overdense environments.
description: 22 pages, 12 figures, 5 tables, submitted to Astronomy & Astrophysics. We welcome the comments from readers
MutexMatch: Semi-Supervised Learning with Mutex-Based Consistency Regularization
Creators: name: Duan, Yue
name: Zhao, Zhen
name: Qi, Lei
name: Wang, Lei
name: Zhou, Luping
name: Shi, Yinghuan
name: Gao, Yang
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: The core issue in semi-supervised learning (SSL) lies in how to effectively leverage unlabeled data, whereas most existing methods tend to put a great emphasis on the utilization of high-confidence samples yet seldom fully explore the usage of low-confidence samples. In this paper, we aim to utilize low-confidence samples in a novel way with our proposed mutex-based consistency regularization, namely MutexMatch. Specifically, the high-confidence samples are required to exactly predict "what it is" by conventional True-Positive Classifier, while the low-confidence samples are employed to achieve a simpler goal -- to predict with ease "what it is not" by True-Negative Classifier. In this sense, we not only mitigate the pseudo-labeling errors but also make full use of the low-confidence unlabeled data by consistency of dissimilarity degree. MutexMatch achieves superior performance on multiple benchmark datasets, i.e., CIFAR-10, CIFAR-100, SVHN, STL-10, mini-ImageNet and Tiny-ImageNet. More importantly, our method further shows superiority when the amount of labeled data is scarce, e.g., 92.23% accuracy with only 20 labeled data on CIFAR-10. Our code and model weights have been released at https://github.com/NJUyued/MutexMatch4SSL.
description: Accepted by IEEE Transactions on Neural Networks and Learning Systems (TNNLS)
Experimental Realization of Type-II Dirac Fermions in PdTe$_2$ Superconductor
Creators: name: Noh, Han-Jin
name: Jeong, Jinwon
name: Cho, En-Jin
name: Kim, Kyoo
name: Min, B. I.
name: Park, Byeong-Gyu
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: A Dirac fermion in a topological Dirac semimetal is a quadruple-degenerate quasi-particle state with a relativistic linear dispersion. Breaking either time-reversal or inversion symmetry turns this system into a Weyl semimetal that hosts double-degenerate Weyl fermion states with opposite chiralities. These two kinds of quasi-particles, although described by a relativistic Dirac equation, do not necessarily obey Lorentz invariance, allowing the existence of so-called type-II fermions. Recent theoretical discovery of type-II Weyl fermions evokes the prediction of type-II Dirac fermions in PtSe$_2$-type transition metal dichalcogenides, expecting an experimental confirmation. Here, we report an experimental realization of type-II Dirac fermions in PdTe$_2$ by angle-resolved photoemission spectroscopy combined with {\it ab-initio} band calculations. Our experimental finding makes the first example that has both superconductivity and type-II Dirac fermions, which turns the topological material research into a new phase.
description: 3 figures
Symmetric ordering and Weyl realizations for quantum Minkowski spaces
Creators: name: Meljanac, Stjepan
name: Škoda, Zoran
name: Kresic-Juric, Sasa
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Symmetric ordering and Weyl realizations for non commutative quantum Minkowski spaces are reviewed. Weyl realizations of Lie deformed spaces and corresponding star products, as well as twist corresponding to Weyl realization and coproduct of momenta are presented. Drinfeld twists understood in Hopf algebroid sense are also discussed. A few examples of corresponding Weyl realizations are given. We show that for the original Snyder space there exists symmetric ordering, but no Weyl realization. Quadratic deformations of Minkowski space are considered and it is demonstrated that symmetric ordering is deformed and a generalized Weyl realization can be defined.
description: 25 pages, to appear in J. Math. Physics
Multiplicative Properties of Quantum Channels
Creators: name: Rahaman, Mizanur
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: Operator Algebras (math.OA)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: In this paper, we study the multiplicative behaviour of quantum channels, mathematically described by trace preserving, completely positive maps on matrix algebras. It turns out that the multiplicative domain of a unital quantum channel has a close connection to its spectral properties. A structure theorem, which reveals the automorphic property of an arbitrary unital quantum channel on a subalgebra, is presented. Various classes of quantum channels (irreducible, primitive etc.) are then analysed in terms of this stabilising subalgebra. The notion of the multiplicative index of a unital quantum channel is introduced, which measures the number of times a unital channel needs to be composed with itself for the multiplicative algebra to stabilise. We show that the maps that have trivial multiplicative domains are dense in completely bounded norm topology in the set of all unital completely positive maps. Some applications in quantum information theory are discussed.
description: Abstract and introduction have been changed. Some new sections are introduced to integrate the application and the theoretical parts. Some new examples are included to compute the multiplicative index, Journal of Physics A:Mathematical and Theoretical (2017)
On-chip Light Trapping in Bilayer Moiré Photonic Crystal Slabs
Creators: name: Tang, Haoning
name: Ni, Xueqi
name: Du, Fan
name: Mazur, Eric
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: There has been remarkable recent progress in the formation of nano-resonators that support ultra-low-loss, compact dielectric photonic crystals with exceptional high-Q modes that operate at visible or telecom wavelengths. New insights into modal engineering have recently emerged from researchers exploring exotic electronic phases in 2D materials. The phenomenon relates to a twist in the angle between two layers of materials with high periodic spatial ordering, such as graphene. A moire pattern forms, and at a particular magic angle of twist, the electronic behavior significantly changes, enjoying a flat energy-momentum dispersion relationship. There is an optical analog to the electron twistronics: bilayer moire photonic crystal slabs can realize a flat-band condition. Under these conditions, the propagating modes have zero group velocity, thus giving rise to momentum-free trapping of Bloch waves in both transverse and vertical directions, creating high quality-factors and exceptionally small modal volumes that eventually lead to the enhancement of the Purcell effect. The dramatically different means of light-localization afforded by moire-structured cavities, very small mode volumes, and spatial determination by the overall moire pattern can manipulate spontaneous emission. This provides many opportunities for applications such as low-threshold lasing, single-photon source, quantum electrodynamics, photonic circuit, and quantum information processing.
Distributed quantum error correction for chip-level catastrophic errors
Creators: name: Xu, Qian
name: Seif, Alireza
name: Yan, Haoxiong
name: Mannucci, Nam
name: Sane, Bernard Ousmane
name: Van Meter, Rodney
name: Cleland, Andrew N.
name: Jiang, Liang
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum error correction holds the key to scaling up quantum computers. Cosmic ray events severely impact the operation of a quantum computer by causing chip-level catastrophic errors, essentially erasing the information encoded in a chip. Here, we present a distributed error correction scheme to combat the devastating effect of such events by introducing an additional layer of quantum erasure error correcting code across separate chips. We show that our scheme is fault tolerant against chip-level catastrophic errors and discuss its experimental implementation using superconducting qubits with microwave links. Our analysis shows that in state-of-the-art experiments, it is possible to suppress the rate of these errors from 1 per 10 seconds to less than 1 per month.
Machine learning based data-driven discovery of nonlinear phase-field dynamics
Creators: name: Kiyani, Elham
name: Silber, Steven
name: Kooshkbaghi, Mahdi
name: Karttunen, Mikko
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: One of the main questions regarding complex systems at large scales concerns the effective interactions and driving forces that emerge from the detailed microscopic properties. Coarse-grained models aim to describe complex systems in terms of coarse-scale equations with a reduced number of degrees of freedom. Recent developments in machine learning (ML) algorithms have significantly empowered the discovery process of the governing equations directly from data. However, it remains difficult to discover partial differential equations (PDEs) with high-order derivatives. In this paper, we present new data-driven architectures based on multi-layer perceptron (MLP), convolutional neural network (CNN), and a combination of CNN and long short-term memory (CNN-LSTM) structures for discovering the non-linear equations of motion for phase-field models with non-conserved and conserved order parameters. The well-known Allen--Cahn, Cahn--Hilliard, and the phase-field crystal (PFC) models were used as the test cases. Two conceptually different types of implementations were used: (a) guided by physical intuition (such as local dependence of the derivatives) and (b) in the absence of any physical assumptions (black-box model). We show that not only can we effectively learn the time derivatives of the field in both scenarios, but we can also use the data-driven PDEs to propagate the field in time and achieve results in good agreement with the original PDEs.
A multipair-free source of entangled photons in the solid state
Creators: name: Neuwirth, Julia
name: Basset, Francesco Basso
name: Rota, Michele B.
name: Hartel, Jan-Gabriel
name: Sartison, Marc
name: da Silva, Saimon F. Covre
name: Jöns, Klaus D.
name: Rastelli, Armando
name: Trotta, Rinaldo
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Unwanted multiphoton emission commonly reduces the degree of entanglement of photons generated by non-classical light sources and, in turn, hampers their exploitation in quantum information science and technology. Quantum emitters have the potential to overcome this hurdle but, so far, the effect of multiphoton emission on the quality of entanglement has never been addressed in detail. Here, we tackle this challenge using photon pairs from a resonantly-driven quantum dot and comparing quantum state tomography and second-order coherence measurements as a function of the excitation power. We observe that the relative (absolute) multiphoton emission probability is as low as $p_m= (5.6 \pm 0.6)10^{-4}$ ($p_2= (1.5 \pm 0.3)10^{-6}$) at the maximum source brightness, values that lead to a negligible effect on the degree of entanglement. In stark contrast with probabilistic sources of entangled photons, we also demonstrate that the multiphoton emission probability and the degree of entanglement remain practically unchanged against the excitation power for multiple Rabi cycles, despite we clearly observe oscillations in the second-order coherence measurements. Our results, explained by a theoretical model that we develop to estimate the actual multiphoton contribution in the two-photon density matrix, highlight that quantum dots can be regarded as a multipair-free source of entangled photons in the solid state.