jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: F. P. A. Vogt | A. Mehner | P. Figueira | S. Yu | F. Kerber | T. Pfrommer | W. Hackenberg | Domenico Bonaccini Calia
Source: arXiv (Cornell University) (preprint, 2023-04-26)
Field: Chemistry — Spectroscopy

The pure-rotational and rotational-vibrational Raman spectrum of the atmosphere at an altitude of 23 km Ground-based optical astronomical observations supported by or in the vicinity of laser guide-star systems can be contaminated by Raman-scattered laser photons. Anticipating, alleviating, and correcting for the impact of this self-inflicted contamination requires a detailed knowledge of the pure-rotational and rotational-vibrational spectrum of the molecules in our atmosphere. We present a 15.3hr-deep combined spectrum of the 4LGSF's 589nm $\approx$ 509THz sodium laser beams of Paranal observatory, acquired with the ESPRESSO spectrograph at a resolution $λ/Δλ\cong140'000\approx0.12$ cm$^{-1}$ and an altitude of 23 km above mean sea level. We identify 865 Raman lines over the spectral range of [3770; 7900]Å$\approx$[+9540; -4315] cm$^{-1}$, with relative intensities spanning ~5 orders of magnitudes. These lines are associated to the most abundant molecules of dry air, including their isotopes: 14N14N, 14N15N, 16O16O, 16O17O, 16O18O, and 12C16O16O. The signal-to-noise of these observations implies that professional observatories can treat the resulting catalogue of Raman lines as exhaustive (for the detected molecules, over the observed Raman shift range) for the purpose of predicting/correcting/exploiting Raman lines in astronomical data. Our observations also reveal that the four laser units of the 4LGSF do not all lase at the same central wavelength. [...] The [measured] offsets [...] are larger than the observed 4LGSF spectral stability of $\pm$3 MHz over hours. They remain well within the operational requirements for creating artificial laser guide-stars, but hinder the assessment of the radial velocity accuracy of ESPRESSO at the required level of 10 m/s. Altogether, our observations demonstrate how Raman lines can be exploited by professional observatories as highly-accurate, on-sky wavelength references. Raman spectroscopy ; Spectrograph ; Physics ; Laser ; Spectral resolution ; Atmosphere (unit) ; Spectral line ; Observatory ; Stars ; Altitude (triangle) ; Astrophysics ; Atomic physics ; Remote sensing ; Optics ; Astronomy ; Meteorology ; Geology Spectroscopy and Laser Applications ; Laser Design and Applications ; Atmospheric Ozone and Climate
Authors: Amy Damitz | Jonah Quirk | Carol E. Tanner | D. S. Elliott
Source: arXiv (Cornell University) (preprint, 2023-11-15)
Field: Chemistry — Inorganic Chemistry

Technique for a direct measurement of the cesium anapole moment using coherent rf and Raman interactions We report progress toward measurements of the electric dipole (E1) transition moments between hyperfine components of the ground state of atomic cesium. This transition is weakly E1 allowed due to weak interactions between nucleons within the nucleus, which lead to a parity-odd current distribution and its associated anapole moment. In this report, we discuss the experimental geometry of our measurement scheme, explore the effects of extraneous fields that can obscure the signal, present initial measurements, analyze the sources and magnitudes of measurement noise, and suggest improvements to the current apparatus. Raman spectroscopy ; Caesium ; Moment (physics) ; Physics ; Atomic physics ; Optics ; Nuclear physics ; Quantum mechanics Radioactive element chemistry and processing ; Radioactive contamination and transfer ; Atomic and Subatomic Physics Research
Authors: Alexander Kruchkov | Shinsei Ryu
Source: arXiv (Cornell University) (preprint, 2023-08-31)
Field: Materials Science — Materials Chemistry

Noise probing of topological band gaps in dispersionless quantum states We uncover a useful connection between the integrated current noise $S(ω)$ and the topological band gap in dispersionless quantum states, $\int d ω[ \mathcal S^{\text{flat}}_{xx} + \mathcal S^{\text{flat}}_{yy} ] = C e^2 Δ^2$ (in units $\hbar$$=$$1$), where $C$ is the Chern number, $e$ is electric charge, and $Δ$ is the topological band gap. This relationship may serve as a working principle for a new experimental probe of topological band gaps in flat band materials. Possible applications include moiré systems, such as twisted bilayer graphene and twisted transition metal dichalcogenides, where a band gap measurement in meV regime presents an experimental challenge. Physics ; Band gap ; Topology (electrical circuits) ; Condensed matter physics ; Omega ; Noise (video) ; Topological quantum number ; Connection (principal bundle) ; Graphene ; Quantum mechanics ; Geometry ; Electrical engineering ; Mathematics ; Image (mathematics) Graphene research and applications ; Topological Materials and Phenomena ; Ga2O3 and related materials
Authors: Priyanka Sinha | Ayan Mondal | Simão M. João | Bheema Lingam Chittari
Source: arXiv (Cornell University) (preprint, 2023-11-10)
Field: Materials Science — Materials Chemistry

Magnetotransport properties of a twisted bilayer graphene in the presence of external electric and magnetic field We extensively investigate the electronic and transport properties of a twisted bilayer graphene when subjected to both an external perpendicular electric field and a magnetic field. Using a basic tight-binding model, we show the flat electronic band properties as well as the density of states (DOS), both without and with the applied electric field. In the presence of an electric field, the degeneracy at the Dirac points is lifted where the non-monotonic behavior of the energy gap exists, especially for twist angles below 3$^\circ$. We also study the behavior of the Landau levels (LL) spectra for different twist angles within a very low energy range. These LL spectra get modified under the influence of the external electric field. Moreover, we calculate the dc Hall conductivity ($σ_{xy}$) for a very large system using the Kernel Polynomial Method (KPM). Interestingly, $σ_{xy}$ makes a transition from a half-integer to an integer quantum Hall effect, \textit{i.e.} the value of $σ_{xy}$ shifts from $\pm 4(n+1/2) (2e^2/h)$ ($n$ is an integer) to $\pm 2n (2e^2/h)$ around a small twist angle of $θ=2.005^\circ$. At this angle, $σ_{xy}$ acquires a Hall plateau at zero Fermi energy. However, the behavior of $σ_{xy}$ remains unaltered when the system is exposed to the electric field, particularly at the magic angle where the bands in both layers can hybridize and strong interlayer coupling plays a crucial role. Condensed matter physics ; Landau quantization ; Physics ; Electric field ; Magnetic field ; Twist ; Bilayer graphene ; Quantum Hall effect ; Magnetization ; Graphene ; Quantum mechanics ; Geometry ; Mathematics Graphene research and applications ; Quantum and electron transport phenomena ; Surface and Thin Film Phenomena
Authors: Adam Overvig | Sander A. Mann | Andrea Alù
Source: arXiv (Cornell University) (preprint, 2023-07-03)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Spatio-Temporal Coupled Mode Theory for Nonlocal Metasurfaces Diffractive nonlocal metasurfaces have recently opened a broad range of exciting developments in nanophotonics research and applications, leveraging spatially extended (yet locally patterned) resonant modes to control light with new degrees of freedom. While conventional grating responses are elegantly captured by temporal coupled mode theory (TCMT), TCMT is not well equipped to capture the more sophisticated responses observed in the nascent field of nonlocal metasurfaces. Here, we introduce spatio-temporal coupled mode theory (STCMT), capable of elegantly capturing the key features of the resonant response of wavefront-shaping nonlocal metasurfaces. This framework can quantitatively guide nonlocal metasurface design, and is compatible with local metasurface frameworks, making it a powerful tool to rationally design and optimize a broad class of ultrathin optical components. We validate this STCMT framework against full-wave simulations of various nonlocal metasurfaces, demonstrating that this tool offers a powerful semi-analytical framework to understand and model the physics and functionality of these devices, without the need for computationally intense full-wave simulations. We also discuss how this model may shed physical insights into nonlocal phenomena in photonics and into the functionality of the resulting devices. As a relevant example, we showcase STCMT's flexibility by applying it to study and rapidly prototype nonlocal metasurfaces that spatially shape thermal emission. Physics ; Flexibility (engineering) ; Metamaterial ; Wavefront ; Photonics ; Degrees of freedom (physics and chemistry) ; Field (mathematics) ; Mode (computer interface) ; Computer science ; Nanophotonics ; Key (lock) ; Optics ; Human–computer interaction Metamaterials and Metasurfaces Applications ; Thermal Radiation and Cooling Technologies ; Plasmonic and Surface Plasmon Research
Authors: Fedor Kovalev | Ilya V. Shadrivov
Source: arXiv (Cornell University) (preprint, 2023-08-22)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Parametric metasurfaces for electromagnetic wave amplification We study parametric amplification of electromagnetic waves using metasurfaces. We design a variable capacitor-loaded metasurface that can amplify incident electromagnetic waves. We analyze various regimes of operation of the system and find that we can achieve a significant gain (over 10 dB) in just one layer of such a structure, and this gain can be controlled by parametric modulation. We study the instability threshold for this system and show that a simple theoretical model agrees well with the results of full numerical simulations. Parametric statistics ; Physics ; Electromagnetic radiation ; Modulation (music) ; Acoustics ; Optics ; Capacitor ; Instability ; Mechanics ; Mathematics Metamaterials and Metasurfaces Applications ; Advanced Antenna and Metasurface Technologies ; Plasmonic and Surface Plasmon Research
Authors: W. Satuła | M. A. Bentley | Amir Jalili | S. Uthayakumaar
Source: arXiv (Cornell University) (preprint, 2023-08-07)
Field: Chemistry — Inorganic Chemistry

Sensitivity study of mirror energy differences in positive parity bands of T=3/2 A=45 nuclei Symmetry conserving density functional theory (DFT) based no-core-configuration-interaction framework (DFT-NCCI) is an excellent tool for precision calculation of diverse (pseudo-)observables related to isospin symmetry breaking from elusive isospin impurities trough isospin corrections to superallowed beta decays to mirror- and triplet-displacement energies and mirror energy differences (MED) along rotational bands. In our recent work [Phys. Rev. C {\bf 106}, 024327 (2022)] we performed axial DFT-NCCI calculations and failed to reproduce a sign of MED in positive-parity bands of 45Sc/45Cr T=3/2 mirror pair what casts a shadow on credibility of the model. In this work we aim to perform a thorough analysis of this case with the focus on sensitivity of our predictions with respect to: (i) low-energy constants (LECs) of our effective contact charge symmetry breaking (CSB) force and (ii) nuclear shape. We demonstrate, among the other, that inclusion of triaxial positive-parity ground-state - which is actually the global positive-parity minimum in our unconstrained mean-field calculation - in the DFT-NCCI calculations instead of the axial one used before leads to MED which are consistent with experimental data concerning both their sign as well as magnitude without any need for fine-tuning of the model's LECs. Isospin ; Physics ; Parity (physics) ; Observable ; Symmetry breaking ; Mirror nuclei ; Nuclear physics ; Atomic physics ; Quantum mechanics Inorganic Fluorides and Related Compounds ; Advanced Chemical Physics Studies ; Superconductivity in MgB2 and Alloys
Authors: Odysseas Tsilipakos | Thomas Koschny
Source: arXiv (Cornell University) (preprint, 2023-03-30)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Multiresonant metasurfaces for arbitrarily-broadband pulse chirping and dispersion compensation We show that ultrathin metasurfaces with a specific multiresonant response can enable simultaneously arbitrarily-strong and arbitrarily-broadband dispersion compensation, pulse (de-)chirping and compression or broadening. This breakthrough overcomes the fundamental limitations of both conventional non-resonant approaches (bulky) and modern singly-resonant metasurfaces (narrowband) for quadratic phase manipulations of electromagnetic signals. The required non-uniform trains of resonances in the electric and magnetic sheet conductivities that completely control phase delay, group delay, and chirp, are rigorously derived and the limitations imposed by fundamental physical constraints are thoroughly discussed. Subsequently, a practical, truncated approximation by finite sequences of physically-realizable linear resonances is constructed and the associated error is quantified. By appropriate spectral ordering of the resonances, operation can be achieved either in transmission or reflection mode, enabling full space coverage. The proposed concept is not limited to dispersion compensation, but introduces a generic and powerful ultrathin platform for the spatio-temporal control of broadband real-world signals with a myriad of applications in modern optics, microwave photonics, radar and communication systems. Narrowband ; Chirp ; Broadband ; Dispersion (optics) ; Pulse compression ; Physics ; Group delay and phase delay ; Metamaterial ; Optics ; Compensation (psychology) ; Phase (matter) ; Electronic engineering ; True time delay ; Reflection (computer programming) ; Computer science ; Photonics ; Pulse (music) ; Radar ; Bandwidth (computing) ; Telecommunications ; Engineering ; Antenna (radio) ; Phased array Metamaterials and Metasurfaces Applications ; Advanced Antenna and Metasurface Technologies ; Antenna Design and Analysis
Authors: Steven A. Kivelson | Akshat Pandey | Anisha G. Singh | A. Kapitulnik | I. R. Fisher
Source: arXiv (Cornell University) (preprint, 2023-08-25)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Emergent $\mathbb{Z}_2$ symmetry near a CDW multicritical point We consider the critical behavior associated with incommensurate unidirectional charge-density-wave ordering in a weakly orthorhombic system subject to uniaxial strain as an experimentally significant example of $U(1)\times U(1)$ multicriticality. We show that, depending on microscopic details, the phase diagram can have qualitatively different structures which can involve a vestigial meta-nematic critical point, a pair of tricritical points, a decoupled tetracritical point, or (at least at mean-field level) a bicritical point. We analyze the emergent symmetries in the critical regime and find that these can -- at least in some cases -- involve an emergent $\mathbb{Z}_2$ order parameter symmetry. Tricritical point ; Multicritical point ; Phase diagram ; Condensed matter physics ; Physics ; Orthorhombic crystal system ; Symmetry (geometry) ; Critical exponent ; Critical point (mathematics) ; Point (geometry) ; Homogeneous space ; Order (exchange) ; Mathematical physics ; Phase (matter) ; Phase transition ; Quantum mechanics ; Mathematics ; Geometry ; Diffraction Organic and Molecular Conductors Research ; High-pressure geophysics and materials ; Physics of Superconductivity and Magnetism
Authors: Eko Tavip Maryanto | Rezza Ruzuqi
Source: Material Science Research India (article, 2023-05-31)
Field: Materials Science — Polymers and Plastics

Investigation of Natural Composites Matoa Tree Wood as the Base Material for Eco-Friendly House Piles using Ansys Composite materials, in simple terms, are materials that have a multi-phase system composed of reinforcing materials and matrix materials. Composite materials are divided into two types, namely synthetic composite materials and natural composite materials. Wood is a natural composite material consisting of a reinforcement and a matrix. The wood of the matoa tree (Pometia vinnata) is known for its good mechanical strength. The comparison of compressive mechanical strength in this study was conducted on matoa wood and ironwood tree wood (eusideroxylon zwageri). This was performed as supporting data in the discussion of natural composite materials of matoa tree wood as the foundation for environmentally friendly house piles. FEM (Finite Element Method) is a numerical method that analyzes the compressive strength of retaining walls. In this study, the 2D analysis used to determine the compressive strength of the natural composite material of Matoa tree wood. In this study, Matoa wood and ironwood were analyzed for compressive strength using FEM. In this research, three different finite element numbers are based on the software. The Ansys software is used to simulate compressive strength. The results obtained were matoa wood and ironwood, respectively A1 = 6.07e^(-07) MPa, A2 = 1.11e^(-06) MPa, and A3 = 2.09e^(-06) MPa and B1 = 1.17e ^(-06) MPa, B2 = 2.13e^(-06) MPa, and B3 = 4.02e^(-06) MPa. These results indicated that the resistance to mechanical compression test of ironwood tree was greater than matoa tree. However, when it was seen based on the perspective of the impact on the environment, Matoa tree has environmentally friendly properties that are effective and efficient. This is supported by the nature of the matoa tree which is easy to cultivate and its roots do not damage other plants. Compressive strength ; Composite number ; Composite material ; Materials science ; Finite element method ; Environmentally friendly ; Compression (physics) ; Structural engineering ; Engineering Natural Fiber Reinforced Composites ; Geotechnical and construction materials studies ; Bamboo properties and applications
Authors: Shishir Khandelwal | Shashwat Kumar | Nicolas Palazzo | Géraldine Haack | Mayeul Chipaux
Source: arXiv (Cornell University) (preprint, 2023-01-30)
Field: Materials Science — Materials Chemistry

Dynamical nuclear polarization for dissipation-induced entanglement in NV centers We propose a practical implementation of a two-qubit entanglement engine which denotes a scheme to generate quantum correlations through purely dissipative processes. On a diamond platform, the electron spin transitions of two Nitrogen-Vacancy (NV) centers play the role of artificial atoms (qubits), interacting through a dipole-dipole Hamiltonian. The surrounding Carbon-13 nuclear spins act as spin baths playing the role of thermal reservoirs at well-defined temperatures and exchanging heat through the NV center qubits. In our scheme, a key challenge is therefore to create a temperature gradient between two spin baths surrounding each NV center, for which we propose the exploit the recent progresses in dynamical nuclear polarization, combined with microscopy superresolution methods. We discuss how these techniques should allow us to initialize such a long lasting out-of-equilibrium polarization situation between them, effectively leading to suitable conditions to run the entanglement engine successfully. Within a quantum master equation approach, we make theoretical predictions using state-of-the-art values for experimental parameters. We obtain promising values for the concurrence, reaching theoretical maxima. Quantum entanglement ; Qubit ; Spins ; Physics ; Dissipative system ; Quantum ; Hamiltonian (control theory) ; Quantum computer ; Diamond ; Dissipation ; Polarization (electrochemistry) ; Quantum mechanics ; Condensed matter physics ; Chemistry Diamond and Carbon-based Materials Research ; Mechanical and Optical Resonators ; Force Microscopy Techniques and Applications
Authors: Stefan Ernst | Patrick Scheidegger | S. Diesch | Christian L. Degen
Source: arXiv (Cornell University) (preprint, 2023-04-05)
Field: Materials Science — Materials Chemistry

Modeling temperature-dependent population dynamics in the excited state of the nitrogen-vacancy center in diamond The nitrogen-vacancy (NV) center in diamond is well known in quantum metrology and quantum information for its favorable spin and optical properties, which span a wide temperature range from near zero to over 600 K. Despite its prominence, the NV center's photo-physics is incompletely understood, especially at intermediate temperatures between 10-100 K where phonons become activated. In this work, we present a rate model able to describe the cross-over from the low-temperature to the high-temperature regime. Key to the model is a phonon-driven hopping between the two orbital branches in the excited state (ES), which accelerates spin relaxation via an interplay with the ES spin precession. We extend our model to include magnetic and electric fields as well as crystal strain, allowing us to simulate the population dynamics over a wide range of experimental conditions. Our model recovers existing descriptions for the low- and high-temperature limits, and successfully explains various sets of literature data. Further, the model allows us to predict experimental observables, in particular the photoluminescence (PL) emission rate, spin contrast, and spin initialization fidelity relevant for quantum applications. Lastly, our model allows probing the electron-phonon interaction of the NV center and reveals a gap between the current understanding and recent experimental findings. Nitrogen-vacancy center ; Excited state ; Condensed matter physics ; Phonon ; Diamond ; Spin (aerodynamics) ; Population ; Physics ; Relaxation (psychology) ; Vacancy defect ; Atomic physics ; Materials science ; Spins Diamond and Carbon-based Materials Research ; Electronic and Structural Properties of Oxides ; Semiconductor materials and devices
Authors: Xia Zhu | Ke Wu | Stephan W. Anderson | Xin Zhang
Source: arXiv (Cornell University) (preprint, 2023-12-15)
Field: Materials Science — Polymers and Plastics

Wearable Coaxially-shielded Metamaterial for Magnetic Resonance Imaging Recent advancements in metamaterials have yielded the possibility of a wireless solution to improve signal-to-noise ratio (SNR) in magnetic resonance imaging (MRI). Unlike traditional closely packed local coil arrays with rigid designs and numerous components, these lightweight, cost-effective metamaterials eliminate the need for radio frequency (RF) cabling, baluns, adapters, and interfaces. However, their clinical adoption has been limited by their low sensitivity, bulky physical footprint, and limited, specific use cases. Herein, we introduce a wearable metamaterial developed using commercially available coaxial cable, designed for a 3.0 T MRI system. This metamaterial inherits the coaxially-shielded structure of its constituent coaxial cable, effectively containing the electric field within the cable, thereby mitigating the electric coupling to its loading while ensuring safer clinical adoption, lower signal loss, and resistance to frequency shifts. Weighing only 50g, the metamaterial maximizes its sensitivity by conforming to the anatomical region of interest. MRI images acquired using this metamaterial with various pulse sequences demonstrate an up to 2-fold SNR enhancement when compared to a state-of-the-art 16-channel knee coil. This work introduces a novel paradigm for constructing metamaterials in the MRI environment, paving the way for the development of next-generation wireless MRI technology. Metamaterial ; Shielded cable ; Footprint ; Sensitivity (control systems) ; Electromagnetic coil ; Wearable computer ; Coaxial cable ; Ringing ; Computer science ; Acoustics ; Metamaterial antenna ; Wireless ; Electromagnetic interference ; Electronic engineering ; Antenna (radio) ; Materials science ; Electrical engineering ; Optoelectronics ; Telecommunications ; Physics ; Engineering ; Embedded system ; Microstrip antenna Conducting polymers and applications ; Wireless Power Transfer Systems ; Advanced MRI Techniques and Applications