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Radio-Frequency Pseudo-Null Induced by Light in an Ion Trap

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arXiv 2025年

作者： Chung, Daun Cha, Yonghwan Shon, Hosung Park, Jeonghyun Lee, Woojun Lee, Kyungmin Cho, Beomgeun Choi, Kwangyeul Kim, Chiyoon Yoo, Seungwoo Kim, Suhan Jeong, Uihwan Kang, Jiyong You, Jaehun Kim, Taehyun Dept. of Computer Science and Engineering Seoul National University Seoul08826 Korea Republic of Automation and Systems Research Institute Seoul National University Seoul08826 Korea Republic of NextQuantum Seoul National University Seoul08826 Korea Republic of Institute of Computer Technology Seoul National University Seoul08826 Korea Republic of Inter-University Semiconductor Research Center Seoul National University Seoul08826 Korea Republic of Institute of Applied Physics Seoul National University Seoul08826 Korea Republic of

In a linear radio-frequency (rf) ion trap, the rf null is the point of zero electric field in the dynamic trapping potential where the ion motion is approximately harmonic. When displaced from the rf null, the ion is superimposed by fast oscillations known as micromotion, which can be probed through motion-sensitive light-atom interactions. In this work, we report on the emergence of the rf pseudo-null, a locus of points where the ion responds to light as if it were at the true rf null, despite being displaced from it. The phenomenon is fully explained by accounting for the general two-dimensional structure of micromotion and is experimentally verified under various potential configurations, with observations in great agreement with numerical simulations. The rf pseudo-null manifests as a line in a two-dimensional parameter space, determined by the geometry of the incident light and its overlap with the motional structure of the ion. The true rf null occurs uniquely at the concurrent point of the pseudo-null lines induced by different light sources. © 2025, CC BY.

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Transverse momentum fluctuation in ultra-central Pb+Pb collision at the LHC

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arXiv 2023年

作者： Samanta, Rupam Bhatta, Somadutta Jia, Jiangyong Luzum, Matthew Ollitrault, Jean-Yves AGH University of Science and Technology Faculty of Physics and Applied Computer Science aleja Mickiewicza 30 Cracow30-059 Poland Université Paris Saclay CNRS CEA Institut de Physique Théorique Gif-sur-Yvette91191 France Department of Chemistry Stony Brook University Stony BrookNY11794 United States Physics Department Brookhaven National Laboratory UptonNY11976 United States Instituto de Física Universidade de São Paulo Rua do Matão 1371 Butantã São Paulo05508-090 Brazil

The ATLAS collaboration has recently observed that the variance of the transverse momentum per particle ([pt]), when measured as a function of the collision multiplicity (Nch) in Pb+Pb collisions, decreases by a factor 2 for the largest values of Nch, corresponding to ultra-central collisions. We show that this phenomenon is naturally explained by invoking impact parameter (b) fluctuations, which contribute to the variance, and gradually disappear in ultra-central collisions. It implies that Nch and [pt] are strongly correlated at fixed b, which is explained by the local thermalization of the QGP medium. © 2023, CC BY.

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Wavelength-accurate and wafer-scale process for nonlinear frequency mixers in thin-film lithium niobate

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arXiv 2024年

作者： Xin, C.J. Lu, Shengyuan Yang, Jiayu Shams-Ansari, Amirhassan Desiatov, Boris Magalhães, Letícia S. Ghosh, Soumya S. McGee, Erin Renaud, Dylan Achuthan, Nicholas Zvyagintsev, Arseniy Barton, David Sinclair, Neil Lončar, Marko John A. Paulson School of Engineering and Applied Sciences Harvard University CambridgeMA United States DRS Daylight Solutions 164565 Via Esprillo San DiegoCA United States Faculty of Engineering Bar-Ilan University Ramat-Gan Israel Department of Physics Harvard University CambridgeMA United States Department of Physics Stevens Institute of Technology HobokenNJ United States Department of Materials Science and Engineering Northwestern University EvanstonIL United States

Recent advancements in thin-film lithium niobate (TFLN) photonics have led to a new generation of high-performance electro-optic devices, including modulators, frequency combs, and microwave-to-optical transducers. However, the broader adoption of TFLN-based devices that rely on all-optical nonlinearities have been limited by the sensitivity of quasi-phase matching (QPM), realized via ferroelectric poling, to fabrication tolerances. Here, we propose a scalable fabrication process aimed at improving the wavelength-accuracy of optical frequency mixers in TFLN. In contrast to the conventional pole-before-etch approach, we first define the waveguide in TFLN and then perform ferroelectric poling. This sequence allows for precise metrology before and after waveguide definition to fully capture the geometry imperfections. Systematic errors can also be calibrated by measuring a subset of devices to fine-tune the QPM design for remaining devices on the wafer. Using this method, we fabricated a large number of second harmonic generation devices aimed at generating 737 nm light, with 73% operating within 5 nm of the target wavelength. Furthermore, we also demonstrate thermo-optic tuning and trimming of the devices via cladding deposition, with the former bringing ∼ 96% of tested devices to the target wavelength. Our technique enables the rapid growth of integrated quantum frequency converters, photon pair sources, and optical parametric amplifiers, thus facilitating the integration of TFLN-based nonlinear frequency mixers into more complex and functional photonic systems. © 2024, CC BY.

关键词： Thin films

Spirometer and sEMG respiratory patterns for clinical decision support system

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Spirometer and sEMG respiratory patterns for clinical decisi...

IEEE Instrumentation and Measurement technology Conference

作者： Amit Krishan Kumar Mansour H. Assaf Voicu Z. Groza Emil M. Petriu Faculty of Electrical-Electronic Engineering Duy Tan University Da Nang Vietnam Key Laboratory of Complex System Intelligent Control and Decision School of Automation Beijing Institute of Technology Beijing China School of Information Technology Engineering Mathematics and Physics The University of the South Pacific Suva Republic of Fiji School of Electrical Engineering and Computer Science University of Ottawa Ottawa Canada

To improve support system for subjects with respiratory ailments, this work analyses the respiratory patterns from spirometer and surface electromyography (sEMG). The patterns are integrated with risk and biochemical systems model to optimise the clinical decision support system (CDSS). The work considers terminal events for the spirometer and sEMG. The events and their associated patterns are correlated and projected on a hyperspace prior implementing it in decision support system. The proposed method shows that the different characteristics of breathing indicate some essential hidden information which when used as 4D scattered projection, optimises the decision making in CDSS. The analysis shows the effectiveness of bimodal respiratory patterns for different breathing capacities, which is promising for the modelled conditions.

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Effective Landé factors for an electrostatically defined quantum point contact in silicene

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arXiv 2021年

作者： Rzeszotarski, Bartlomiej Mreńca-Kolasińska, Alina Peeters, François M. Szafran, Bartlomiej AGH University of Science and Technology Faculty of Physics and Applied Computer Science al. Mickiewicza 30 Kraków30-059 Poland Department of Physics National Cheng Kung University Tainan70101 Taiwan Universiteit Antwerpen Departement Fysica Groenenborgerlaan 171 AntwerpenB-2020 Belgium

The transconductance and effective Landé g∗ factors for a quantum point contact defined in silicene by the electric field of a split gate is investigated. The strong spin-orbit coupling in buckled silicene reduces the g∗ factor for in-plane magnetic field from the nominal value 2 to around 1.2 for the first- to 0.45 for the third conduction subband. However, for perpendicular magnetic field we observe an enhancement of g∗ factors for the first subband to 5.8 in nanoribbon with zigzag and to 2.5 with armchair edge. The main contribution to the Zeeman splitting comes from the intrinsic spin-orbit coupling defined by the Kane-Mele form of interaction. Copyright © 2021, The Authors. All rights reserved.

关键词： Silicene

Fractional Brownian motion with random Hurst exponent: accelerating diffusion and persistence transitions

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arXiv 2022年

作者： Balcerek, Michal Burnecki, Krzysztof Thapa, Samudrajit Wylomańska, Agnieszka Chechkin, Aleksei Faculty of Pure and Applied Mathematics Hugo Steinhaus Center Wroclaw University of Science and Technology Wyspianskiego 27 Wroclaw50-370 Poland School of Mechanical Engineering Tel Aviv University Tel Aviv6997801 Israel Sackler Center for Computational Molecular and Materials Science Tel Aviv University Tel Aviv6997801 Israel Institute for Physics & Astronomy University of Potsdam Potsdam-Golm14476 Germany Akhiezer Institute for Theoretical Physics National Science Center Kharkov Institute of Physics and Technology’ Akademicheskaya st.1 Kharkov61108 Ukraine

Fractional Brownian motion, a Gaussian non-Markovian self-similar process with stationary long-correlated increments, has been identified to give rise to the anomalous diffusion behavior in a great variety of physical systems. The correlation and diffusion properties of this random motion are fully characterized by its index of self-similarity, or the Hurst exponent. However, recent single particle tracking experiments in biological cells revealed highly complicated anomalous diffusion phenomena that can not be attributed to a class of self-similar random processes. Inspired by these observations, we here study the process which preserves the properties of fractional Brownian motion at a single trajectory level, however, the Hurst index randomly changes from trajectory to trajectory. We provide a general mathematical framework for analytical, numerical and statistical analysis of fractional Brownian motion with random Hurst exponent. The explicit formulas for probability density function, mean square displacement and autocovariance function of the increments are presented for three generic distributions of the Hurst exponent, namely two-point, uniform and beta distributions. The important features of the process studied here are accelerating diffusion and persistence transition which we demonstrate analytically and numerically. © 2022, CC BY.

关键词： Diffusion

Masterclass on information visualization for games research 20

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Masterclass on information visualization for games research

7th ACM SIGCHI Annual Symposium on computer-Human Interaction in Play, CHI PLAY 2020

作者： Wallner, Günter Kriglstein, Simone Eindhoven University of Technology Eindhoven Netherlands University of Applied Arts Vienna Vienna Austria University of Vienna Faculty of Computer Science Vienna Austria AIT Austrian Institute of Technology GmbH Vienna Austria

ISBN: (纸本)9781450375870

This CHI PLAY 2020 masterclass offers an introduction into information visualization and how it can assist in the analysis and communication of the wide variety of data gathered in games-related research. The goal is to provide an overview of easy-to-apply visualizations for both quantitative and qualitative data frequently used within the CHI PLAY community, including survey, textual, relational, and spatial data. It is intended for everyone interested in how to represent and communicate data in an easily-understandable way. © 2020 Owner/Author.

关键词： Data Analytics

Observation of the dual quantum spin Hall insulator by density-tuned correlations in a van der Waals monolayer

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arXiv 2024年

作者： Tang, Jian Ding, Thomas Siyuan Chen, Hongyu Gao, Anyuan Qian, Tiema Huang, Zumeng Sun, Zhe Han, Xin Strasser, Alex Li, Jiangxu Geiwitz, Michael Shehabeldin, Mohamed Belosevich, Vsevolod Wang, Zihan Wang, Yiping Watanabe, Kenji Taniguchi, Takashi Bell, David C. Wang, Ziqiang Fu, Liang Zhang, Yang Qian, Xiaofeng Burch, Kenneth S. Shi, Youguo Ni, Ni Chang, Guoqing Xu, Su-Yang Ma, Qiong Department of Physics Boston College Chestnut HillMA United States Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore Singapore Department of Chemistry and Chemical Biology Harvard University CambridgeMA United States Department of Physics and Astronomy and California NanoSystems Institute University of California Los Angeles Los AngelesCA United States Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing China Department of Materials Science and Engineering Texas A&M University College StationTX United States Department of Physics and Astronomy University of Tennessee KnoxvilleTN United States Min H. Kao Department of Electrical Engineering and Computer Science University of Tennessee KnoxvilleTN United States Research Center for Electronic and Optical Materials National Institute for Materials Science Tsukuba Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science Tsukuba Japan Harvard John A. Paulson School of Engineering and Applied Sciences The Center for Nanoscale system Harvard University CambridgeMA United States Department of Physics Massachusetts Institute of Technology CambridgeMA United States CIFAR Azrieli Global Scholars program CIFAR Toronto Canada

The convergence of topology and correlations represents a highly coveted realm in the pursuit of novel quantum states of matter [1, 2]. Introducing electron correlations to a quantum spin Hall (QSH) insulator can lead to the emergence of a fractional topological insulator and other exotic time-reversal-symmetric topological order [3- 10], not possible in quantum Hall and Chern insulator systems. However, the QSH insulator with quantized edge conductance remains rare, let alone that with significant correlations. In this work, we report a novel dual QSH insulator within the intrinsic monolayer crystal of TaIrTe4, arising from the interplay of its single-particle topology and density-tuned electron correlations. At charge neutrality, monolayer TaIrTe4 demonstrates the QSH insulator that aligns with single-particle band structure calculations, manifesting enhanced nonlocal transport and quantized helical edge conductance. Interestingly, upon introducing electrons from charge neutrality, TaIrTe4 only shows metallic behavior in a small range of charge densities but quickly goes into a new insulating state, entirely unexpected based on TaIrTe4's single-particle band structure. This insulating state could arise from a strong electronic instability near the van Hove singularities (VHS), likely leading to a charge density wave (CDW). Remarkably, within this correlated insulating gap, we observe a resurgence of the QSH state, marked by the revival of nonlocal transport and quantized helical edge conduction. Our observation of helical edge conduction in a CDW gap could bridge spin physics and charge orders. The discovery of a dual QSH insulator introduces a new method for creating topological flat minibands via CDW superlattices, which offer a promising platform for exploring time-reversal-symmetric fractional phases and electromagnetism [3-5, 11, 12]. Copyright © 2024, The Authors. All rights reserved.

关键词： Charge density waves

Conditional entropy and information of quantum processes

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arXiv 2024年

作者： Das, Siddhartha Goswami, Kaumudibikash Pandey, Vivek International Institute of Information Technology Gachibowli Telangana Hyderabad500032 India QICI Quantum Information and Computation Initiative Department of Computer Science The University of Hong Kong Pokfulam Road Hong Kong Institute of Physics Faculty of Physics Astronomy and Informatics Nicolaus Copernicus University Grudziadzka 5/7 Toruń87-100 Poland Harish-Chandra Research Institute A CI of Homi Bhabha National Institute Chhatnag Road Jhunsi Prayagraj211019 India

What would be a reasonable definition of the conditional entropy of bipartite quantum processes, and what novel insight would it provide? We develop this notion using four information-theoretic axioms and define the corresponding quantitative formulas. Our definitions of the conditional entropies of channels are based on the generalized state and channel divergences, for instance, quantum relative entropy. We find that the conditional entropy of quantum channels has potential to reveal insights for quantum processes that aren’t already captured by the existing entropic functions, entropy or conditional entropy, of the states and channels. The von Neumann conditional entropy S[A|B]N of the channel NA′B′→AB is based on the quantum relative entropy, with system pairs A′, A and B′, B being nonconditioning and conditioning systems, respectively. We identify a connection between the underlying causal structure of a bipartite channel and its conditional entropy. In particular, we provide a necessary and sufficient condition for a bipartite quantum channel NA′B′→AB in terms of its von Neumann conditional entropy S[A|B]N, to have no causal influence from A′ to B. As a consequence, if S[A|B]N ′ to B. Our definition of the conditional entropy establishes the strong subadditivity of the entropy for quantum channels. We also study the total amount of correlations possible due to quantum processes by defining the multipartite mutual information of quantum channels. Copyright © 2024, The Authors. All rights reserved.

关键词： Quantum channel