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Blue-Detuned Magneto-optical Trap of CaF Molecules

Physical Review Letters 2024年第23期132卷 233402-233402页

作者： Samuel J. Li Connor M. Holland Yukai Lu Lawrence W. Cheuk Department of Physics Department of Electrical and Computer Engineering

A key method to produce trapped and laser-cooled molecules is the magneto-optical trap (MOT), which is conventionally created using light red detuned from an optical transition. In this work, we report a MOT for CaF molecules created using blue-detuned light. The blue-detuned MOT (BDM) achieves temperatures well below the Doppler limit and provides the highest densities and phase-space densities reported to date in CaF MOTs. Our results suggest that BDMs are likely achievable in many relatively light molecules including polyatomic ones, but our measurements suggest that BDMs will be challenging to realize in substantially heavier molecules due to sub-mK trap depths. In addition to record temperatures and densities, we find that the BDM substantially simplifies and enhances the loading of molecules into optical tweezer arrays, which are a promising platform for quantum simulation and quantum information processing. Notably, the BDM reduces molecular number requirements ninefold compared to a conventional red-detuned MOT, while not requiring additional hardware. Our work therefore substantially simplifies preparing large-scale molecular tweezer arrays, which are a novel platform for simulation of quantum many-body dynamics and quantum information processing with molecular qubits.

关键词： Cold and ultracold molecules Light-matter interaction Molecules Cooling & trapping

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Nano-structured metamaterial absorber based on a plus-shaped resonator for optical wavelength applications

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Journal of engineering and applied Science 2024年第1期71卷 1-16页

作者： Islam, Istiaq Mohammad Tanvirul Islam, Sikder Sunbeam Islam, Md. Rashedul Karim, Abu Naser Md. Rezaul Azim, Rezaul Department of Electrical and Electronic Engineering International Islamic University Chittagong Chittagong Bangladesh Department of Computer Science and Engineering International Islamic University Chittagong Chittagong Bangladesh Department of Physics Chittagong University Chittagong Bangladesh

Metamaterial absorbers have sparked widespread interest due to their remarkable electromagnetic properties, which enable a wide range of applications in light absorption and manipulation. This study introduces a new three-layer nanomaterial absorber (NMA) unit cell composed of nickel (Ni), silicon dioxide (SiO2), and nickel (Ni) designed to operate across the entire visible spectrum (390–780 nm). We demonstrate the NMA’s exceptional absorption characteristics through rigorous numerical simulations using industry-standard software, achieving a mean absorption rate of 97.17% and a maximum absorption peak of 99.99% at 694.89 nm under standard angles. Furthermore, the NMA unit cell has good impedance matching, efficient coupling between capacitors and inductors, and significant plasmonic resonance properties. Fabrication feasibility and potential applications in solar energy harvesting, optical sensing, and light detection. © The Author(s) 2024.

关键词： Silica

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Broadband suppression of laser intensity noise based on second-harmonic generation

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Physical Review applied 2024年第1期22卷 014026-014026页

作者： Y. Li F. Seddighi G. Porat Department of Electrical and Computer Engineering Department of Physics

We present a novel method for the suppression of laser intensity noise and pulse-to-pulse energy fluctuation, based on second-harmonic generation. This method is broadband, passive, has low complexity, and suppresses noise uniformly over the noise spectrum. We theoretically model, analytically analyze, and numerically simulate this technique’s performance for cw and nanosecond pulse lasers with different pulse shapes. We demonstrate broadband relative intensity noise suppression of up to 48 dB, and pulse-to-pulse energy fluctuation suppression of up to 50 dB, and highlight the significance of these findings for extending atom trap storage time, e.g., for quantum information processing.

关键词： Lasers Noise Photonics Second order nonlinear optical processes Laser techniques Optical lattices & traps Optical second-harmonic generation

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Stability of topologically protected slow light against disorder

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Physical Review A 2024年第6期109卷 063507-063507页

作者： Jonas F. Karcher Sarang Gopalakrishnan Mikael C. Rechtsman Department of Physics Department of Electrical and Computer Engineering

Slowing down light in on-chip photonic devices strongly enhances the light-matter interaction, but typically also leads to increased backscattering and small-bandwidth operation. It was shown recently that, if one modifies the edge termination of a photonic Chern insulator such that the edge mode wraps many times around the Brillouin zone, light can be slowed to arbitrarily low group velocity over a large bandwidth, without being subject to backscattering. Here we study the robustness of these in-gap slow light modes against fabrication disorder, finding that disorder on scales significantly larger than the minigaps between edge bands is tolerable. We identify the mechanism for wavepacket breakup as disorder-induced velocity renormalization and calculate the associated breakup time.

关键词： Optics & lasers Photonic crystals Topological effects in photonic systems

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New insights on thermal ageing of electrical insulating oils as revealed from photoluminescence and absorption spectroscopy

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High Voltage 2024年第5期9卷 1033-1045页

作者： Hesham S.Karaman Eman G.Atiya Diaa-Eldin A.Mansour Mohsen Ghali Z.M.S.Elbarbary Manal M.Emara Department of Electrical Engineering Faculty of Engineering at ShoubraBenha UniversityCairoEgypt Department of Electrical Power and Machines Engineering Faculty of EngineeringTanta UniversityTantaEgypt Department of Electrical Power Engineering Faculty of EngineeringEgypt-Japan University of Science and Technology(E-JUST)New Borg El-Arab CityAlexandriaEgypt Department of Energy Materials Institute of Basic and Applied ScienceEgypt-Japan University of Science and Technology(E-JUST)New Borg El-Arab CityAlexandriaEgypt Department of Physics Faculty of ScienceKafrelsheikh UniversityKafrelsheikhEgypt Department of Electrical Engineering College of EngineeringKing Khalid UniversityAbhaSaudi Arabia Center for Engineering and Technology Innovations King Khalid UniversityAbhaSaudi Arabia Department of Electrical Engineering Faculty of EngineeringKafrelsheikh UniversityKafrelsheikhEgypt

Recently,significant efforts have been exerted to replace mineral oil with environmentally friendly oils due to safety and environmental ***,there is a need to clarify the physical mechanisms behind the ageing impact of these *** authors use advanced optical spectroscopy techniques in correlation with dielectric measurements to understand the ageing processes in environmentally friendly oils as well as mineral ***,different samples of environmentally friendly oils and mineral oil were utilised to investigate the ageing *** samples were subjected to different ageing periods using a thermal accelerated ageing ***,the severity of the produced byproducts due to the oil degradation is examined based on several measured properties representing macroscopic and microscopic *** macroscopic category was evaluated through dielectric properties,including breakdown voltage,dielectric permittivity,and dissipation *** microscopic category,on the other hand,was assessed using techniques such as ultraviolet-visible absorption spectroscopy and photoluminescence *** techniques enabled a deep understanding of the molecular-level changes occurring in the oil under ageing conditions,thereby getting new insights into oil ageing *** is worth mentioning that natural ester oil demonstrated the most favourable performance across various properties under ageing conditions.

关键词： absorption thermal spectroscopy

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Entanglement entropy of free fermions in timelike slices

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Physical Review B 2024年第14期110卷 144306页

作者： Bowei Liu Hao Chen Biao Lian Department of Physics Department of Electrical and Computer Engineering

We define the entanglement entropy of free fermion quantum states in an arbitrary space-time slice of a discrete set of points and particularly investigate timelike (causal) slices. For one-dimensional lattice free fermions with an energy bandwidth E0, we calculate the time-direction entanglement entropy SA in a time-direction slice of a set of times tn=nτ (1≤n≤K) spanning a time length t on the same site. For zero-temperature ground states, we find that SA shows volume law when τ≫τ0=2π/E0; in contrast, SA∼13lnt when τ=τ0, and SA∼16lnt when τ<τ0, resembling the Calabrese-Cardy formula for one flavor of nonchiral and chiral fermion, respectively. For finite-temperature thermal states, the mutual information also saturates when τ<τ0. For noneigenstates, volume law in t and signatures of the Lieb-Robinson bound velocity can be observed in SA. For generic space-time slices with one point per site, the zero-temperature entanglement entropy shows a clear transition from area law to volume law when the slice varies from spacelike to timelike.

关键词： Entanglement entropy Quantum entanglement Quantum statistical mechanics Free-electron model Lattice models in condensed matter

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Single-bit full adder and logic gate based on synthetic antiferromagnetic bilayer skyrmions

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Rare Metals 2022年第7期41卷 2249-2258页

作者： Kai Yu Mak Jing Xia Xi-Chao Zhang Li Li Mouad Fattouhi Motohiko Ezawa Xiao-Xi Liu Yan Zhou School of Science and Engineering The Chinese University of Hong KongShenzhen 518172China College of Physics and Electronic Engineering Sichuan Normal UniversityChengdu 610068China Department of Electrical and Computer Engineering Shinshu UniversityNagano 380-8553Japan Department of Applied Physics University of SalamancaSalamanca 37008Spain Department of Applied Physics University of TokyoTokyo 113-8656Japan

Skyrmion-based devices are promising candi-dates for non-volatile memory and low-delay time *** skyrmion-based devices execute operation by controlling skyrmion trajectory,which can be impeded by the skyrmion Hall ***,the design of skyrmion-based arithmetic devices built on synthetic antiferromag-netic(SyAF)structures is presented,where the structure can greatly suppress skyrmion Hall *** this study,the operations of skyrmion-based half adder,full adder,and XOR logic gate are executed by introducing geometric notches and tilted edges,which can annihilate or diverge *** of these skyrmion-based devices is evaluated,where the delay time and energy-delay product of the single-bit full adder are 1.95 ns and 2.50×10^(-22)Js,which are only 12%and 79%those of the previously proposed skyrmion-based single-bit full *** improvement is significant in the construction of ripple-carry adder and ripple-carry ***,our skyrmion-based SyAF arithmetic device is a promising candidate to develop high-speed spintronic devices.

关键词： Skyrmion Full adder Synthetic antiferromagnet Lowdelaytime electronics Micromagnets

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Development of Mechatronic Solution on Hot-Stamping Heads 33rd

Development of Mechatronic Solution on Hot-Stamping Heads

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33rd International Conference on Organization and Technology of Maintenance, OTO 2024

作者： Ostojić, Ivan Velimirović, Mirjana Kovačević, Nada Ratković Dihovicni, Djordje Computer-Mechanical Engineering Section Department of Electrical and Computer Engineering Academy of Technical Applied Studies Belgrade Belgrade Serbia Urban Technics Valjevo Serbia

ISBN: (纸本)9783031805967

The general goal of the research is to reduce loss of productivity, failure and downtime and the percentage of waste in production in the company, which is already committed to and successful in applying standards, raising the quality of service, as well as occupational safety and environmental protection. In this scientific paper a mechatronic subsystem is designed and implemented, as an addition to the hot-stamping production line, which would monitor whether there are present (and whether there are in quantities enough of) each of the three thermoplastic, metallized strips, which line the product - profiled lath. When it is detected and recognized that the tape will soon be used up, the sub-system automatically signals this with turning off heating of the slat and activating a sound alarm, attracting attention of the human operator. The heater switches off automatically if the strip loss has occurred (event driven system), in order to prevent deformation of the slat profile. The subsystem includes automatic monitoring of the remaining amount of tape, alarm notification in case of imminent disappearance of the tape, with the heater turned off and alarming the operator. The human operator then has enough time to replace the tape (approximately five to ten minutes, depending on the product). The subsystem described above is designed, built, implemented, tested and put in operation. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

关键词： Quality of service

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Design of an improved Fractional Order PID controller using Variable Set-Point Control Scheme 3

Design of an improved Fractional Order PID controller using ...

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3rd IEEE International Conference on Control, Instrumentation, Energy and Communication, CIEC 2024

作者： Mukherjee, Nishant Chakraborty, Biswajit Sen, Kausik University of Calcutta Instrumentation Engineering Department of Applied Physics Kolkata India Jadavpur University Department of Electrical Engineering Kolkata India

ISBN: (纸本)9798350313703

This paper presents a novel control strategy for Fractional Order PID (FOPID) controllers i.e., Variable Set-Point Weighted Variable Fractional Order PID (VSPWVFOPID) controller. To implement this control scheme, three different values of set-point weighting factor (β), integral order (λ) and differential order (μ) are selected for three different regions of output response and applied to set-point, integral action, and differential action, respectively. The key focus of this control scheme is to provide satisfactory results in both, initial transient and load rejection phases as well as superior robust control. The effectiveness of the proposed VSPW-VFOPID controller is demonstrated considering two different process models and their 10% perturbed systems in MATLAB simulation platform. The performance of the proposed control scheme is compared with existing control techniques like Ziegler Nichols (ZN) tuning, Fixed Set Point Weighting (FSPW), Variable Set Point Weighting (VSPW), and Fractional Order PID (FOPID). In this context, VSPW-VFOPID can provide better response during both phases. For the purpose of this paper, various performance indices are considered like Percentage Overshoot (OS%), Rise-Time (tr), Peak-Time (tp), Settling-Time (ts), Integral Absolute Error (IAE), Integral Square Error (ISE), and Integral Time Absolute Error (ITAE). From the results of the proposed scheme, it can be concluded that, apart from enhanced robust control, VSPW-VFOPID shows excellent performance during initial set-point tracking and load rejection phases which makes it superior to other existing control schemes. © 2024 IEEE.

关键词： Simulation platform

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Solar thermal application and optimization of a staircase-shaped resonator broadband solar absorber

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Optical and Quantum Electronics 2024年第12期56卷 1-14页

作者： Alsharari, Meshari Muheki, Jonas Surve, Jaymit Armghan, Ammar Aliqab, Khaled Patel, Shobhit K. Department of Electrical Engineering. College of Engineering Jouf University Sakaka72388 Saudi Arabia Department of physics Biological and medical physics University of Houston HoustonTX United States Department of Electrical Engineering Marwadi University Gujarat Rajkot360003 India Department of Computer Engineering Marwadi University Gujarat Rajkot360003 India

The development of efficient energy absorbers is essential for optimizing solar energy utilization, particularly for applications such as thermophotovoltaics and other solar energy harvesting technologies. Current research typically focuses on improving the efficiency of the solar absorbers with low-cost materials. This study addresses this limitation by introducing a broadband solar absorber with a staircase-shaped resonator structure. The absorber employs tungsten as the substrate due to its high thermal conductivity and stability, with a GaInAsP layer forming the staircase resonator. Simulations using finite element methods demonstrate that the proposed two-layered structure achieves over 90% absorption within the 200–3000 nm wavelength range, including ultraviolet and visible spectra. This broad absorption range maximizes solar energy capture and conversion efficiency. A parametric examination demonstrates how geometric factors like substrate depth and resonator dimensions affect the absorption effectiveness. The unique staircase shape of the resonator enhances light trapping and absorption across the full spectrum. Under real-world conditions, the absorber effectively captures solar energy across various angles and polarizations. These findings contribute to the advancement of energy absorber design and offer insights for future innovations in solar energy harvesting. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.

关键词： Stairs

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