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arXiv 2023年

作者： Biswas, Abhijit Alvarez, Gustavo A. Li, Tao Christiansen-Salameh, Joyce Jeong, Eugene Puthirath, Anand B. Iyengar, Sathvik Ajay Li, Chenxi Gray, Tia Zhang, Xiang Pieshkov, Tymofii S. Kannan, Harikishan Elkins, Jacob Vajtai, Robert Birdwell, A. Glen Neupane, Mahesh R. Garratt, Elias J. Pate, Bradford B. Ivanov, Tony G. Zhao, Yuji Tian, Zhiting Ajayan, Pulickel M. Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Sibley School of Mechanical and Aerospace Engineering Cornell University IthacaNY14853 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States DEVCOM Army Research Laboratory RF Devices and Circuits AdelphiMD20783 United States Naval Research Laboratory Chemistry Division WashingtonDC20375 United States

Heterostructures based on ultrawide-bandgap (UWBG) semiconductors (bandgap >4.0 eV), such as boron nitride (BN) and diamond, hold significant importance for the development of high-power electronics in the next generation. However, achieving in-situ hetero-epitaxy of BN/diamond or vice versa remains exceptionally challenging due to the complex growth kinetics involved. In this study, we have grown BN thin film on (100) single crystal diamonds using pulsed laser deposition and investigated its structural, magnetic, optical, and thermal properties. The structural analyses confirmed the growth of BN films, which exhibited diamagnetic behavior at room temperature. Notably, the film demonstrated anisotropic refractive index characteristics within the visible-to-near-infrared wavelength range. The room temperature cross-plane thermal conductivity of BN is 1.53 (± 0.77) W/mK, while the thermal conductance of the BN/diamond interface is 20 (± 2) MW/m2K. These findings have significant implications for a range of device applications based on UWBG BN/diamond heterostructures. © 2023, CC BY.

关键词： Diamonds

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A parameter-free differential evolution algorithm for the analytic continuation of imaginary time correlation functions

arXiv

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arXiv 2022年

作者： Nichols, Nathan S. Sokol, Paul Del Maestro, Adrian Data Science and Learning Division Argonne National Laboratory ArgonneIL60439 United States Department of Physics University of Vermont BurlingtonVT05405 United States Materials Science Program University of Vermont BurlingtonVT05404 United States Department of Physics Indiana University BloomingtonIN47408 United States Department of Physics and Astronomy University of Tennessee KnoxvilleTN37996 United States Min H. Kao Department of Electrical Engineering and Computer Science University of Tennessee KnoxvilleTN37996 United States

We report on Differential Evolution for Analytic Continuation (DEAC): a parameter-free evolutionary algorithm to generate the dynamic structure factor from imaginary time correlation functions. Our approach to this long-standing problem in quantum many-body physics achieves enhanced spectral fidelity while using fewer compute (CPU) hours. The need for fine-tuning of algorithmic control parameters is eliminated by embedding them within the genome to be optimized for this evolutionary computation based algorithm. Benchmarks are presented for models where the dynamic structure factor is known exactly, and experimentally relevant results are included for quantum Monte Carlo simulations of bulk 4He below the superuid transition temperature. Copyright © 2022, The Authors. All rights reserved.

关键词： Functional analysis

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Enhanced Superconducting Qubit Performance Through Ammonium Fluoride Etch

arXiv

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arXiv 2024年

作者： Kopas, Cameron J. Goronzy, Dominic P. Pham, Thang Torres Castanedo, Carlos G. Cheng, Matthew Cochrane, Rory Nast, Patrick Lachman, Ella Zhelev, Nikolay Z. Vallières, André Murthy, Akshay A. Oh, Jin-Su Zhou, Lin Kramer, Matthew J. Cansizoglu, Hilal Bedzyk, Michael J. Dravid, Vinayak P. Romanenko, Alexander Grassellino, Anna Mutus, Josh Y. Hersam, Mark C. Yadavalli, Kameshwar Rigetti Computing BerkeleyCA United States Department of Materials Science and Engineering Northwestern University EvanstonIL United States Center for Applied Physics and Superconducting Technologies Northwestern University EvanstonIL United States Department of Physics and Astronomy Northwestern University EvanstonIL United States Department of Physics University of Oregon EugeneOR United States Graduate Program in Applied Physics Northwestern University EvanstonIL60208 United States Fermi National Accelerator Laboratory BataviaIL United States Ames Laboratory U.S. Department of Energy AmesIA United States Northwestern University EvanstonIL United States Department of Chemistry Northwestern University EvanstonIL United States Department of Electrical and Computer Engineering Northwestern University EvanstonIL United States

The performance of superconducting qubits is often limited by dissipation and two-level systems (TLS) losses. The dominant sources of these losses are believed to originate from amorphous materials and defects at interfaces and surfaces, likely as a result of fabrication processes or ambient exposure. Here, we explore a novel wet chemical surface treatment at the Josephson junction-substrate and the substrate-air interfaces by replacing a buffered oxide etch (BOE) cleaning process with one that uses hydrofluoric acid followed by aqueous ammonium fluoride. We show that the ammonium fluoride etch process results in a statistically significant improvement in median T1 by ∼ 22% (p = 0.002), and a reduction in the number of strongly-coupled TLS in the tunable frequency range. Microwave resonator measurements on samples treated with the ammonium fluoride etch prior to niobium deposition also show ∼ 33% lower TLS-induced loss tangent compared to the BOE treated samples. As the chemical treatment primarily modifies the Josephson junction-substrate interface and substrate-air interface, we perform targeted chemical and structural characterizations to examine materials’ differences at these interfaces and identify multiple microscopic changes that could contribute to decreased TLS. © 2024, CC BY-NC-ND.

关键词： Fluorine compounds

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Synergetic Effect of Nonthermal Plasma and Supported Cobalt Catalyst in Plasma-Enhanced Co2 Hydrogenation

SSRN

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SSRN 2022年

作者： Song, Chunshan Wang, Jiajie Wang, Xiaoxing AlQahtani, Mohammad S. Knecht, Sean D. Bilén, Sven G. Chu, Wei Department of Chemical Engineering Sichuan University Chengdu610065 China Clean Fuels & Catalysis Program EMS Energy Institute Department of Energy and Mineral Engineering The Pennsylvania State University University ParkPA16802 United States Department of Chemical Engineering The Pennsylvania State University University ParkPA16802 United States School of Engineering Design Technology and Professional Programs The Pennsylvania State University University ParkPA16802 United States School of Electrical Engineering and Computer Science The Pennsylvania State University University ParkPA16802 United States Department of Chemistry Faculty of Science The Chinese University of Hong Kong NT Hong Kong Shatin China

Nonthermal plasma can provide an alternative to CO 2 utilization under mild conditions. Understanding the effect of plasma on catalysis is highly desired. Herein, a comparative study was performed on CO 2 hydrogenation under thermal catalytic and plasma catalytic conditions using an alumina-supported cobalt catalyst. Significant plasma-catalyst synergy was attained at the low-temperature range between 423 K and 498 K where the CO 2 conversion increased up to approximately 3.6 times of the sum of that using plasma or catalyst individually. The plasma-catalytic reaction showed a significantly lower activation energy (~40 kJ/mol), which is only half of that in the thermal catalytic reaction (~80 kJ/mol). Kinetic analysis and DRIFTS results indicate that CO 2 activation is promoted by plasma with the assistance of active H species from gas phase. Furthermore, the total H 2 adsorption capacity and the coverage of unrecyclable adsorbed H species on the metal surface were decreased under plasma. The promotion effect is very likely due to a new reaction pathway introduced by plasma. In addition, the structure and morphology changes of spent catalysts after thermal or plasma reaction were not significant, suggesting they contribute little to the synergetic effect observed under the conditions. © 2022, The Authors. All rights reserved.

关键词： Carbon dioxide

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Ultrastrong Spin-Photon Coupling in Gadolinium Gallium Garnet

Ultrastrong Spin-Photon Coupling in Gadolinium Gallium Garne...

引用

Conference on Lasers and Electro-Optics (CLEO)

作者： T. Elijah Kritzell Junzhe Bao Jacques Doumani Jae Joon Lee Hongjing Xu Fuyang Tay Hiroyuki Nojiri Motoaki Bamba Andrey Baydin Junichiro Kono Department of Electrical and Computer Engineering Rice University Houston Texas USA Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston Texas USA Department of Physics and Astronomy Rice University Houston Texas USA Institute for Materials Research Tohoku University Senai Japan The Hakubi Center for Advanced Research Kyoto University Kyoto Japan Department of Physics I Kyoto University Kyoto Japan Smalley-Curl Institute Rice University Houston Texas USA Department of Material Science and NanoEngineering Rice University Houston Texas USA

We examine ultrastrong coupling of an ensemble of paramagnetic spins in Gd 3 Ga 5 O 12 with terahertz photons in the presence of a high external magnetic field both in the bulk and thin-film limits.

ISBN: (纸本)9781957171258

We examine ultrastrong coupling of an ensemble of paramagnetic spins in Gd 3 Ga 5 O 12 with terahertz photons in the presence of a high external magnetic field both in the bulk and thin-film limits.

关键词： CCD cameras Condensed matter Magnetic fields Photons Quantum optics Terahertz spectroscopy

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Compressibility-Near-Zero Acoustic Radiation

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Physical Review Applied 2021年第2期15卷 024022-024022页

作者： Curtis Rasmussen Andrea Alù Department of Mechanical Engineering The University of Texas at Austin Austin Texas 78712 USA Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78712 USA Photonics Initiative CUNY Advanced Science Research Center New York New York 10031 USA Physics Program Graduate Center City University of New York New York New York 10026 USA

A hallmark of near-zero-index materials is the uniform phase profile that the waves experience as they propagate with staticlike properties in these media. This feature is exploited in electromagnetics for several applications, including for the realization of compact highly directive antennas illuminated by a single source. Here, we discuss the promise of near-zero metamaterials for acoustic radiation, based on the cutoff of a higher-order mode in a waveguide with small holes. We show that the near-zero nature of this phenomenon ensures unusual robustness to disorder, which is analyzed using a statistical description of the radiation patterns for randomly generated location of the holes. The radiation pattern can be made more directive by simply increasing the overall radiating aperture, without having to worry about the specific location of individual holes and their relative distance. The proposed zero-compressibility material offers a promising alternative to traditional acoustic directive sources due to its design simplicity, inherent robustness, and compact profile.

关键词： Acoustic metamaterials Acoustic wave phenomena Disordered systems Acoustic techniques Cavity resonators Green's function methods

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Van der Waals device integration beyond the limits of van der Waals forces via adhesive matrix transfer

arXiv

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arXiv 2023年

作者： Satterthwaite, Peter F. Zhu, Weikun Jastrzebska-Perfect, Patricia Tang, Melbourne Gao, Hongze Kitadai, Hikari Lu, Ang-Yu Tan, Qishuo Tang, Shin-Yi Chueh, Yu-Lun Kuo, Chia-Nung Lue, Chin Shan Kong, Jing Ling, Xi Niroui, Farnaz Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Department of Chemical Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Department of Chemistry Boston University BostonMA02215 United States Department of Materials Science and Engineering National Tsing Hua University Hsinchu30013 Taiwan Semiconductor Research Center Hon Hai Research Institute Taipei11492 Taiwan College of Semiconductor Research National Tsing Hua University Hsinchu30013 Taiwan Department of Physics National Cheng Kung University Tainan70101 Taiwan Taiwan Consortium of Emergent Crystalline Materials National Science and Technology Council Taipei10601 Taiwan Program on Key Materials Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan70101 Taiwan Division of Materials Science and Engineering Boston University BostonMA02215 United States The Photonics Center Boston University BostonMA02215 United States

Pristine van der Waals (vdW) interfaces between two-dimensional (2D) and other materials are core to emerging optical and electronic devices. Their direct fabrication is, however, challenged as the vdW forces are weak and cannot be tuned to accommodate integration of arbitrary layers without solvents, sacrificial-layers or high-temperatures, steps that can introduce damage. To address these limitations, we introduce a single-step 2D material-to-device integration approach in which forces promoting transfer are decoupled from the vdW forces at the interface of interest. We use this adhesive matrix transfer to demonstrate conventionally-forbidden direct integration of diverse 2D materials (MoS2, WSe2, PtS2, GaS) with dielectrics (SiO2, Al2O3), and scalable, aligned heterostructure formation, both foundational to device development. We then demonstrate a single-step integration of monolayer-MoS2 into arrays of transistors. With no exposure to polymers or solvents, clean interfaces and pristine surfaces are preserved, which can be further engineered to demonstrate both n- and p-type behavior. Beyond serving as a platform to probe the intrinsic properties of sensitive nanomaterials without the influence of processing steps, our technique allows efficient formation of unconventional device form-factors, with an example of flexible transistors demonstrated. Copyright © 2023, The Authors. All rights reserved.

关键词： Van der Waals forces

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Unitary Excitation Transfer between Coupled Cavities Using Temporal Switching

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Physical Review Letters 2021年第1期127卷 013902-013902页

作者： Yarden Mazor Michele Cotrufo Andrea Alù Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78712 USA School of Electrical Engineering Tel-Aviv University Ramat-Aviv Tel-Aviv 69978 Israel Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA Physics Program Graduate Center of the City University of New York New York New York 10016 USA

Tailored time variations can enable efficient control over signal flows, giving rise to exotic wave phenomena. In this work, we demonstrate how abrupt temporal switching of the coupling between two cavities can tailor the energy flow between them beyond the limitations of static scenarios, enabling unitary excitation transfer. The proposed scheme is robust with respect to a wide range of nonidealities, with implications for classical and quantum phenomena, from computing to nanophotonic systems.

关键词： Metamaterials Coupled oscillators

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Two-dimensional Bose-Hubbard model for helium on graphene

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Physical Review B 2021年第23期103卷 235414-235414页

作者： Jiangyong Yu Ethan Lauricella Mohamed Elsayed Kenneth Shepherd, Jr. Nathan S. Nichols Todd Lombardi Sang Wook Kim Carlos Wexler Juan M. Vanegas Taras Lakoba Valeri N. Kotov Adrian Del Maestro Department of Physics University of Vermont Burlington Vermont 05405 USA Materials Science Program University of Vermont Burlington Vermont 05405 USA Department of Physics and Astronomy University of Missouri Columbia Missouri 65211 USA Department of Mathematics & Statistics University of Vermont Burlington Vermont 05405 USA Department of Physics and Astronomy University of Tennessee Knoxville Tennessee 37996 USA Min H. Kao Department of Electrical Engineering and Computer Science University of Tennessee Knoxville Tennessee 37996 USA

An exciting development in the field of correlated systems is the possibility of realizing two-dimensional (2D) phases of quantum matter. For a system of bosons, an example of strong correlations manifesting themselves in a 2D environment is provided by helium adsorbed on graphene. We construct the effective Bose-Hubbard model for this system which involves hard-core bosons (U≈∞), repulsive nearest-neighbor (V>0) and small attractive (V′<0) next-nearest-neighbor interactions. The mapping onto the Bose-Hubbard model is accomplished by a variety of many-body techniques which take into account the strong He-He correlations on the scale of the graphene lattice spacing. Unlike the case of dilute ultracold atoms where interactions are effectively pointlike, the detailed microscopic form of the short-range electrostatic and long-range dispersion interactions in the helium-graphene system is crucial for the emergent Bose-Hubbard description. The result places the ground state of the first layer of He4 adsorbed on graphene deep in the commensurate solid phase with 1/3 of the sites on the dual triangular lattice occupied. Because the parameters of the effective Bose-Hubbard model are very sensitive to the exact lattice structure, this opens up an avenue to tune quantum phase transitions in this solid-state system.

关键词： Adsorption Quantum phase transitions Graphene Helium-4 superfluids Bose-Hubbard model Density functional theory Extended Hubbard model Quantum Monte Carlo Wannier function methods

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Phase-induced frequency conversion and doppler effect with time-modulated metasurfaces

arXiv

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arXiv 2021年

作者： Ramaccia, Davide Sounas, Dimitrios L. Alù, Andrea Toscano, Alessandro Bilotti, Filiberto Department of Engineering ROMA TRE University Via Vito Volterra 62 Rome00146 Italy Department of Electrical and Computer Engineering Wayne State University DetroitMI48202 United States Photonics Initiative Advanced Science Research Center Physics Program Graduate Center Department of Electrical Engineering City College City University of New York New YorkNY10031 United States

Metasurfaces consisting of electrically thin and densely packed planar arrays of subwavelength elements enable an unprecedented control of the impinging electromagnetic fields. Spatially modulated metasurfaces can efficiently tailor the spatial distribution of these fields with great flexibility. Similarly, time modulated metasurfaces can be successfully used to manipulate the frequency content and time variations of the impinging field. In this paper, we present time-modulated reflective metasurfaces that cause a frequency shift to the impinging radiation, thus realizing an artificial Doppler effect in a non-moving electrically thin structure. Starting from the theoretical analysis, we analytically derive the required time modulation of the surface admittance to achieve this effect, and present a realistic time-varying structure, based on a properly designed and dynamically tuned high-impedance surface. It is analytically and numerically demonstrated that the field emerging from the metasurface is up-/down-converted in frequency according to the modulation profile of the metasurface. The proposed metasurface concept, enabling a frequency modulation of the electromagnetic field "on-the-fly", may find application in telecommunication, radar, and sensing scenarios. Copyright © 2021, The Authors. All rights reserved.

关键词： Doppler effect

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