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Back action in quantum electro-optic sampling of electromagnetic vacuum fluctuations

Physical Review Research 2023年第1期5卷 013151-013151页

作者： T. L. M. Guedes I. Vakulchyk D. V. Seletskiy A. Leitenstorfer A. S. Moskalenko Guido Burkard Department of Physics and Center for Applied Photonics University of Konstanz D-78457 Konstanz Germany Center for Theoretical Physics of Complex Systems Institute for Basic Science (IBS) Daejeon 34126 Republic of Korea Basic Science Program Korea University of Science and Technology (UST) Daejeon Korea 34113 Republic of Korea Department of Engineering Physics Polytechnique Montréal Montréal QC Canada H3T 1J4 Department of Physics KAIST Daejeon 34141 Republic of Korea

The influence of measurement back action on electro-optic sampling of electromagnetic quantum fluctuations is investigated. Based on a cascaded treatment of the nonlinear interaction between a near-infrared coherent probe and the mid-infrared vacuum, we account for the generated electric-field contributions that lead to detectable back action. Specifically, we theoretically address two realistic setups, exploiting one or two probe beams for the nonlinear interaction with the quantum vacuum, respectively. The setup parameters at which back action starts to considerably contaminate the measured noise profiles are determined. We find that back action starts to detrimentally affect the signal once the fluctuations due to the coupling to the mid-infrared vacuum become comparable to the base shot noise. Due to the vacuum fluctuations entering at the beam splitter, the shot noise of two incoming probe pulses in different channels is uncorrelated. Therefore, even when the base shot noise dominates the output of the experiment, it does not contribute to the correlation signal itself. However, we find that further contributions due to nonlinear shot-noise enhancement are still present. Ultimately, a regime in which electro-optic sampling of quantum fields can be considered as effectively back-action free is found.

关键词： Nonlinear optical susceptibility Optical coherence Optical tests of quantum theory Quantum field theory (low energy) Quantum fluctuations & noise Quantum information processing Quantum measurements Quantum states of light Ultrafast optics

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Not all spacetime coordinates for general-relativistic ray tracing are created equal

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Physical Review D 2023年第8期108卷 084004-084004页

作者： Gabriele Bozzola Chi-kwan Chan Vasileios Paschalidis Department of Astronomy University of Arizona Tucson AZ United States Data Science Institute University of Arizona Tucson AZ United States Department of Physics University of Arizona Tucson AZ United States Program in Applied Mathematics University of Arizona Tucson AZ United States

Models for the observational appearance of astrophysical black holes rely critically on accurate general-relativistic ray tracing and radiation transport to compute the intensity measured by a distant observer. In this paper, we illustrate how the choice of coordinates and initial conditions affect this process. In particular, we show that propagating rays from the camera to the source leads to different solutions if the spatial part of the momentum of the photon points towards the horizon or away from it. In doing this, we also show that coordinates that are well suited for numerical general-relativistic magnetohydrodynamic (GRMHD) simulations are typically not optimal for generic ray tracing. We discuss the implications for black hole images and show that radiation transport in optimal and nonoptimal spacetime coordinates lead to the same images up to numerical errors and algorithmic choices.

关键词： Classical black holes General relativity Accretion disk & black-hole plasma Astronomical black holes Numerical techniques Relativistic magnetohydrodynamics

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

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Nature Electronics 2024年第1期7卷 17-28页

作者： Satterthwaite, Peter F. Zhu, Weikun Jastrzebska-Perfect, Patricia Tang, Melbourne Spector, Sarah O. 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 CambridgeMA United States Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA United States Department of Chemical Engineering Massachusetts Institute of Technology CambridgeMA United States Department of Physics Massachusetts Institute of Technology CambridgeMA United States Department of Chemistry Boston University BostonMA United States Department of Materials Science and Engineering National Tsing Hua University Hsinchu Taiwan Semiconductor Research Center Hon Hai Research Institute Taipei Taiwan College of Semiconductor Research National Tsing Hua University Hsinchu Taiwan Department of Physics National Cheng Kung University Tainan Taiwan Taiwan Consortium of Emergent Crystalline Materials National Science and Technology Council Taipei Taiwan Program on Key Materials Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan Taiwan Division of Materials Science and Engineering Boston University BostonMA United States The Photonics Center Boston University BostonMA United States

Pristine van der Waals (vdW) heterostructures formed between two-dimensional (2D) and other materials can be used to create optical and electronic devices. However, the weak vdW forces alone do not allow direct physical stacking of arbitrary layers. As a result, vdW heterostructure fabrication typically requires solvents, sacrificial layers or high temperatures, which can introduce damage and contaminants. Here, we show that adhesive matrix transfer can eliminate these limitations and can provide vdW integration beyond the limits of vdW forces. In the approach, a hybrid high- and low-adhesion surface is used to decouple the forces driving the transfer from the vdW forces defining the heterostructure of interest. We show that the technique can be used to achieve direct vdW integration of diverse 2D materials (MoS2, WSe2, PtS2 and GaS) with dielectrics (SiO2 and Al2O3), which is conventionally forbidden but critical for active devices and scalable, aligned heterostructure formation. The approach also allows single-step 2D material-to-device integration, which we illustrate by fabricating arrays of monolayer MoS2 transistors. As any exposure to solvents or polymers is avoided, the interfaces and surfaces remain pristine. Thus, intrinsic 2D material properties can be probed without the influence of processing steps. The materials can be further engineered through surface treatments and used to fabricate unconventional device form factors. © 2023, The Author(s), under exclusive licence to Springer Nature Limited.

关键词： Van der Waals forces

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Unavoidable multilevel biaxial symmetry breaking in chiral hybrid liquid crystals

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Physical Review E 2025年第4期111卷 045410-045410页

作者： Jin-Sheng Wu Marina Torres Lázaro Souvik Ghosh Haridas Mundoor Henricus H. Wensink Ivan I. Smalyukh Department of Physics and Chemical Physics Program University of Colorado Boulder Colorado 80309 USA Laboratoire de Physique des Solides–UMR 8502 Université Paris-Saclay and CNRS 91405 Orsay France International Institute for Sustainability with Knotted Chiral Meta Matter Hiroshima University Higashihiroshima Japan Department of Electrical Computer and Energy Engineering Materials Science and Engineering Program and Soft Materials Research Center University of Colorado Boulder Colorado 80309 USA Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado Boulder Colorado 80309 USA

Chiral nematic or cholesteric liquid crystals (LCs) are fluid mesophases with long-ranged orientational order featuring a quasilayered periodicity imparted by a helical director configuration but lacking long-range positional order. Doping molecular cholesteric LCs with strongly anisotropic uniaxial colloidal particles adds another level of complexity because of the interplay between weak surface-anchoring boundary conditions and bulk-based elastic distortions near the particle-LC interface. Using cylindrical colloidal disks and rods with different geometric shapes and surface conditions, we demonstrate that these colloidal inclusions generically exhibit biaxial orientational probability distributions which may impart anomalously strong local biaxiality onto the hybrid cholesteric LC structure. Unlike nonchiral hybrid molecular-colloidal LCs, where biaxial order emerges only at critical colloid volume fractions exceeding some uniaxial-biaxial transition value, the orientational probability of the colloidal inclusions immersed in chiral nematic hosts is unambiguously biaxial even at infinite dilution. We demonstrate that the colloids induce local biaxial perturbations within the molecular orientational order of the LC host medium which strongly enhances the weak but native biaxial order of chiral nematic LC induced by the chiral symmetry breaking of the director field. With the help of analytical modeling and computer simulations based on the Landau–de Gennes free energy of the host LC around the colloids, we rationalize the observed multilevel biaxial order and conclude that it is not only unavoidable but also strongly enhanced compared to both achiral hybrid LCs and purely molecular cholesteric LCs.

关键词： Cholesteric liquid crystals

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The Effect of Music and Light-Color as a Machine Empathic Response on Stress in Occupational Health

The Effect of Music and Light-Color as a Machine Empathic Re...

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International Conference on Control, Decision and Information Technologies (CoDIT)

作者： André s Felipe Dorado Karl Daher Elena Mugellini Denis Lalanne Omar Abou Khaled Master in Computer Science BeNeFri program University of Bern Switzerland University of Applied Sciences of Western Switzerland Fribourg Switzerland Human-IST University of Fribourg Fribourg Switzerland

In a world where technological advancements are progressing at a vertiginous pace, social networks, online games, virtual worlds, streaming services, and remote work are part of everyday life. This is the case for the work environment, with the use of technological tools and home offices. In contrast, harmful aspects have been amplified, such as stress that affects occupational health. Lately, considerable interest has been gained in the affective domain in improving the occupational situation using empathic responses. In this work, we study the effect of machine empathic responses such as blue light, relaxing music, and the combination of light and music on people performing stressful tasks in an occupational environment. Thirty five participants tested different stimuli, eleven tested the music condition, twelve the light effect, and another twelve the combination of light and music. The monitoring of the heart rate variability along with psychological measures show that empathic responses can help reduce humans stress levels.

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Red emission from strain-relaxed bulk InGaN active region

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Optics Express 2025年第13期33卷 27245-27254页

作者： Zuojian Pan Zhizhong Chen Haodong Zhang Chuhan Deng Ling Hu Fei Huang Xiaohang Li Qi Wang Guoyi Zhang Bo Shen State Key Laboratory for Artificial Microstructure and Mesoscopic Physics School of Physics Peking University Beijing 100871 China Dongguan Institute of Optoelectronics Peking University Dongguan Guangdong 523808 China Yangtze Delta Institute of Optoelectronics Peking University Nantong Jiangsu 226000 China Advanced Semiconductor Laboratory Electrical and Computer Engineering Program CEMSE Division King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia

High-In-content InGaN quantum wells (QWs) in red light-emitting diodes (LEDs) are typically grown at low temperatures to ensure effective In incorporation. In this study, red LEDs based on bulk InGaN active region were demonstrated. The growth temperature of bulk InGaN was ∼800℃, which is over 100℃ higher than the typical growth temperature of red QWs. By introducing high-density trench structures in the underlying green multi-quantum wells (MQWs), the compressive strain in bulk InGaN was relaxed by ∼96%. With strain relaxation, phase separation occurred in the bulk InGaN, forming low-In-content (blue) and high-In-content (red) phases. The red phase acted as carrier localization centers, enabling red light emission under electrical injection. The red LEDs based on bulk InGaN active region exhibited superior wavelength stability, with the peak wavelength shifting slightly from 648.6 nm at 1 mA to 642.4 nm at 100 mA. Meanwhile, the on-wafer peak external quantum efficiency was measured to be 0.32%. To the best of our knowledge, this study presents a new epitaxial strategy for red InGaN LEDs.

关键词： Green light emitting diodes Quantum efficiency Quantum wells Red light emitting diodes Scanning electron microscopy Stark effect

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Two-Step Machine Learning Approach for Charge-Transfer Coupling with Structurally Diverse Data

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Journal of Physical Chemistry A 2024年第1期128卷 271-280页

作者： Lin, Hung-Hsuan Wang, Chun-I Yang, Chou-Hsun Secario, Muhammad Khari Hsu, Chao-Ping Institute of Chemistry Academia Sinica 128 Section 2 Academia Road Nankang Taipei115 Taiwan Taiwan International Graduate Program on Sustainable Chemical Science & Technology Academia Sinica Institute of Chemistry 128 Academia Road Sec.2 Nankang Taipei115 Taiwan Department of Applied Chemistry National Yang Ming Chiao Tung University 1001 University Road Hsinchu300 Taiwan Division of Physics National Center for Theoretical Sciences 1 Section 4 Roosevelt Road Taipei106 Taiwan Molecular Science and Digital Innovation Center Genetics Generation Advancement Corp No. 28 Ln. 36 Xinhu First Rd. Neihu Taipei114 Taiwan Department of Chemistry University of Illinois at Urbana-Champaign UrbanaIL61801 United States

Electronic coupling is important in determining charge-transfer rates and dynamics. Coupling strength is sensitive to both intermolecular, e.g., orientation or distance, and intramolecular degrees of freedom. Hence, it is challenging to build an accurate machine learning model to predict electronic coupling of molecular pairs, especially for those derived from the amorphous phase, for which intermolecular configurations are much more diverse than those derived from crystals. In this work, we devise a new prediction algorithm that employs two consecutive KRR models. The first model predicts molecular orbitals (MOs) from structural variation for each fragment, and coupling is further predicted by using the overlap integral included in a second model. With our two-step procedure, we achieved mean absolute errors of 0.27 meV for an ethylene dimer and 1.99 meV for a naphthalene pair, much improved accuracy amounting to 14-fold and 3-fold error reductions, respectively. In addition, MOs from the first model can also be the starting point to obtain other quantum chemical properties from atomistic structures. This approach is also compatible with a MO predictor with sufficient accuracy. © 2023 American Chemical Society.

关键词： Molecular orbitals

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Variational Transformer Ansatz for the Density Operator of Steady States in Dissipative Quantum Many-Body Systems

arXiv

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arXiv 2025年

作者： Wei, Lu Jia, Zhian Wang, Yufeng Kaszlikowski, Dagomir Ling, Haibin Department of Applied Mathematics & Statistics Stony Brook University Stony BrookNY11794 United States Program of Data Science Stony Brook University Stony BrookNY11794 United States Centre for Quantum Technologies National University of Singapore SG 117543 Singapore Department of Physics National University of Singapore SG 117543 Singapore Department of Computer Science Stony Brook University Stony BrookNY11794 United States

The transformer architecture, known for capturing long-range dependencies and intricate patterns, has extended beyond natural language processing. Recently, it has attracted significant attention in quantum information and condensed matter physics. In this work, we propose the transformer density operator ansatz for determining the steady states of dissipative quantum many-body systems. By vectorizing the density operator as a many-body state in a doubled Hilbert space, the transformer encodes the amplitude and phase of the state’s coefficients, with its parameters serving as variational variables. Our design preserves translation invariance while leveraging attention mechanisms to capture diverse long-range correlations. We demonstrate the effectiveness of our approach by numerically calculating the steady states of dissipative Ising and Heisenberg spin chain models, showing that our method achieves excellent accuracy in predicting steady states. © 2025, CC BY.

关键词： Hilbert spaces

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Analysis of Partial Discharges in Oil-Impregnated Transformer Paper Insulation and PET-G Insulation

IEEE Open Journal of Instrumentation and Measurement

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IEEE Open Journal of Instrumentation and Measurement 2025年 4卷

作者： Kameli, Sayed Mohammad Abuelrub, Abdelaziz AlShaikh Saleh, Mohammad Refaat, Shady S. Ghrayeb, Ali Abu-Rub, Haitham Olesz, Marek Texas A&M University at Qatar Electrical and Computer Engineering Department Doha Qatar Texas A&M University Department of Electrical and Computer Engineering College StationTX77843 United States University of Hertfordshire School of Physics Engineering and Computer Science Department of Engineering HatfieldAL10 9EU United Kingdom Hamad Bin Khalifa University Qatar Foundation Electrical and Computer Engineering Program in College of Science and Engineering Doha Qatar Gdańsk University of Technology Department of Electrical Power Engineering Gdańsk80-233 Poland

Partial discharge (PD) is a widespread phenomenon instigated in power transformer (PT) insulation systems. PDs are triggered by voids that vary in size and position within the PT insulation. The electrical characteristics of those damaging, PD-causing cavities must be well understood, to accelerate the development of advanced PD detection techniques. Thus, the impact of varying the radius and position of spherical air voids on the characteristics of PDs in PTs is examined using a 3-D finite element analysis (FEA) model designed in COMSOL Multiphysics. The spherical voids are positioned between two windings of a 512 kV, three-phase (3φ ) PT. The peak electric field (EF) and aggregate energy in the FEA model are used in conjunction with laboratory measurements of the apparent discharge magnitude, for detailed analysis of Polyethylene Terephthalate Glycol (PET-G)-based cylindrical voids with different heights. Simulations demonstrate that the inception of PD activity in the PT model occurs for spherical voids with a radius exceeding 1 mm. Furthermore, the most severe PDs occur within the press-board insulation, adjacent to the uppermost part of the innermost windings. Experiments demonstrate that a significant increase in PD activity was observed for PET-G-based cylindrical voids with heights exceeding 1 mm. © 2022 IEEE.

关键词： Partial discharges

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Internal dose assessment of lymphoma 18F-FDG Positron Emission Tomography (PET) scan

Internal dose assessment of lymphoma 18F-FDG Positron Emissi...

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2023 National physics Seminar, SNF 2023

作者： Murat, H. Karim, M.K.A. Kechik, M.M.A. Amer, M.F. Razak, H.R.A. Kamal, I. Chew, M.T. Department of Physics Faculty of Science Universiti Putra Malaysia Selangor Serdang Malaysia Department of Nuclear Medicine Hospital Sultanah Aminah Johor Bahru Johor Malaysia Medical Imaging Program College of Medicine and Health St Luke's Campus University of Exeter DevonEX1 2LU United Kingdom Medical Imaging Department KPJ Healthcare University Nilai Negeri Sembilan Malaysia Research Centre for Applied Physics and Radiation Technologies School of Engineering and Technology Sunway University Petaling Jaya Malaysia

This study aimed to assess the internal radiation exposure of patients who have undergone a Positron Emission Tomography (PET) scan using 18F-FDG radiopharmaceutical. A total of 24 patients (8 men, 16 women, with an average age of 43.88 ± 18.57 years and weight of 57.54 ± 13.04 kg) who had been diagnosed with lymphoma were administered with 300.80 ± 23.09 MBq of 18F-FDG for a PET scan of the whole body. The IDAC-Dose 2.1 program, developed by the International Commission on Radiological Protection (ICRP), was used to measure absorbed and effective doses. The organs selected for absorbed dose analysis were the breast, kidneys, adrenals, liver, and brain, with the brain receiving the highest absorbed dose and the breast receiving the lowest absorbed dose. The effective dose for all patients was 4.85 ± 0.37 mSv, and the ratio of the effective dose to the administered activity was 1.611 × 10-2 mSv/MBq. The safety of the current practice using 18F-FDG PET scan was ascertained, given that the ratio of effective dose to administered activity was lower than 1.9 x 10-2 mSv/MBq. © Published under licence by IOP Publishing Ltd.

关键词： Positron emission tomography

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