Pub Date : 2024-07-03DOI: 10.1038/s41534-024-00845-6
Seungbeom Chin, Yong-Su Kim, Marcin Karczewski
We propose a graph method for systematically searching for schemes that can generate multipartite entanglement in linear bosonic systems with heralding. While heralded entanglement generation offers more tolerable schemes for quantum tasks than postselected ones, it is generally more challenging to find appropriate circuits for multipartite systems. We show that our graph mapping from boson subtractions provides handy tactics to overcome the limitations in circuit designs. Within our graph framework, we identify enhanced schemes for qubit N-partite GHZ, W, and the superposition of N = 3 GHZ and W states. Furthermore, we have found a qudit N-partite GHZ state generation scheme, which requires substantially fewer particles than previous proposals. These results demonstrate the power of our approach in discovering optimized solutions for the generation of intricate heralded entangled states. We expect our method to serve as a promising tool in generating diverse entanglement.
我们提出了一种图方法，用于系统地搜索能在有预示的线性玻色系统中产生多方纠缠的方案。与后选方案相比，预示纠缠生成为量子任务提供了更多可容忍的方案，但要为多方系统找到合适的电路通常更具挑战性。我们的研究表明，玻色子减法的图映射为克服电路设计的局限性提供了便捷的策略。在我们的图框架内，我们确定了用于 N 比特 N 部分 GHZ、W 以及 N = 3 GHZ 和 W 状态叠加的增强方案。此外，我们还发现了一种四比特 N-partite GHZ 状态生成方案，它所需的粒子数量大大少于之前的方案。这些结果证明了我们的方法在发现生成复杂预示纠缠态的优化方案方面的能力。我们期待我们的方法能成为产生多样化纠缠的一个有前途的工具。
{"title":"Shortcut to multipartite entanglement generation: A graph approach to boson subtractions","authors":"Seungbeom Chin, Yong-Su Kim, Marcin Karczewski","doi":"10.1038/s41534-024-00845-6","DOIUrl":"https://doi.org/10.1038/s41534-024-00845-6","url":null,"abstract":"<p>We propose a graph method for systematically searching for schemes that can generate multipartite entanglement in linear bosonic systems with heralding. While heralded entanglement generation offers more tolerable schemes for quantum tasks than postselected ones, it is generally more challenging to find appropriate circuits for multipartite systems. We show that our graph mapping from boson subtractions provides handy tactics to overcome the limitations in circuit designs. Within our graph framework, we identify enhanced schemes for qubit N-partite GHZ, W, and the superposition of <i>N</i> = 3 GHZ and W states. Furthermore, we have found a qudit N-partite GHZ state generation scheme, which requires substantially fewer particles than previous proposals. These results demonstrate the power of our approach in discovering optimized solutions for the generation of intricate heralded entangled states. We expect our method to serve as a promising tool in generating diverse entanglement.</p>","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":null,"pages":null},"PeriodicalIF":7.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141495899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1103/physrevb.110.035201
Yufei Ge, Weitang Li, Jiajun Ren, Zhigang Shuai
Organic molecular materials are potential high-performance thermoelectric materials. Theoretical understanding of thermoelectric conversion in organic materials is essential for rational molecular design for efficient energy conversion materials. In organic materials, nonlocal electron-phonon coupling plays a vital role in charge transport and leads to complex transport mechanisms, including hopping, phonon assisted, band, and transient localization. In this work, based on the time-dependent density matrix renormalization group method, we look at the role of nonlocal electron-phonon coupling on the thermoelectric conversion in organic systems described by the Holstein-Peierls model. We calculate the current-current correlation and the heat current-current correlation functions. We find that (i) nonlocal electron-phonon coupling has a very weak influence on the Seebeck coefficient because of the cancellation between the heat current-current correlation function and the current-current correlation function, but it has a strong influence on the conductivity through dynamic disorders; and (ii) doping concentration has a strong influence on both the conductivity and Seebeck coefficient, and the optimal doping ratio to reach the highest power factor is 3%–10% fillings when the Holstein-Peierls model is valid. These findings suggest that we can design organic materials with higher power factors by first enhancing mobility through rational design, and then searching for the optimal doping ratio.
{"title":"Roles of nonlocal electron-phonon coupling on the electrical conductivity and Seebeck coefficient: A time-dependent DMRG study","authors":"Yufei Ge, Weitang Li, Jiajun Ren, Zhigang Shuai","doi":"10.1103/physrevb.110.035201","DOIUrl":"https://doi.org/10.1103/physrevb.110.035201","url":null,"abstract":"Organic molecular materials are potential high-performance thermoelectric materials. Theoretical understanding of thermoelectric conversion in organic materials is essential for rational molecular design for efficient energy conversion materials. In organic materials, nonlocal electron-phonon coupling plays a vital role in charge transport and leads to complex transport mechanisms, including hopping, phonon assisted, band, and transient localization. In this work, based on the time-dependent density matrix renormalization group method, we look at the role of nonlocal electron-phonon coupling on the thermoelectric conversion in organic systems described by the Holstein-Peierls model. We calculate the current-current correlation and the heat current-current correlation functions. We find that (i) nonlocal electron-phonon coupling has a very weak influence on the Seebeck coefficient because of the cancellation between the heat current-current correlation function and the current-current correlation function, but it has a strong influence on the conductivity through dynamic disorders; and (ii) doping concentration has a strong influence on both the conductivity and Seebeck coefficient, and the optimal doping ratio to reach the highest power factor is 3%–10% fillings when the Holstein-Peierls model is valid. These findings suggest that we can design organic materials with higher power factors by first enhancing mobility through rational design, and then searching for the optimal doping ratio.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141495667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1103/physrevb.110.035113
Yu-Peng Wang, Chen Fang, Jie Ren
A quantum many-body system subject to unitary evolution and repeated local measurements with an increasing rate undergoes a measurement-induced entanglement transition from extensive (or subextensive) to area law entropy scaling. We find that certain open boundary systems under “generalized monitoring,” consisting of “projective monitoring” and conditional feedback, display an anomalous late-time particle concentration on the edge, reminiscent of the “skin effect” in non-Hermitian systems. Such feedback-induced skin effect will suppress the entanglement generation, rendering the system short-range entangled without measurement-induced entanglement transition. While initially emerged in noninteracting models, such skin effect can also occur in chaotic interacting systems and Floquet quantum circuits subjected to random generalized measurements. Since the dynamics of the skin effect do not require postselection and can be observed at the particle number level, the phenomenon is experimentally relevant and accessible in noisy intermediate-scale quantum platforms, such as trapped ions.
{"title":"Absence of measurement-induced entanglement transition due to feedback-induced skin effect","authors":"Yu-Peng Wang, Chen Fang, Jie Ren","doi":"10.1103/physrevb.110.035113","DOIUrl":"https://doi.org/10.1103/physrevb.110.035113","url":null,"abstract":"A quantum many-body system subject to unitary evolution and repeated local measurements with an increasing rate undergoes a measurement-induced entanglement transition from extensive (or subextensive) to area law entropy scaling. We find that certain open boundary systems under “generalized monitoring,” consisting of “projective monitoring” and conditional feedback, display an anomalous late-time particle concentration on the edge, reminiscent of the “skin effect” in non-Hermitian systems. Such feedback-induced skin effect will suppress the entanglement generation, rendering the system short-range entangled without measurement-induced entanglement transition. While initially emerged in noninteracting models, such skin effect can also occur in chaotic interacting systems and Floquet quantum circuits subjected to random generalized measurements. Since the dynamics of the skin effect do not require postselection and can be observed at the particle number level, the phenomenon is experimentally relevant and accessible in noisy intermediate-scale quantum platforms, such as trapped ions.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141495720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1103/physrevd.110.012001
I. Adachiet al.(Belle II Collaboration)
We present GFlaT, a new algorithm that uses a graph-neural-network to determine the flavor of neutral mesons produced in decays. It improves previous algorithms by using the information from all charged final-state particles and the relations between them. We evaluate its performance using decays to flavor-specific hadronic final states reconstructed in a sample of electron-positron collisions collected at the resonance with the Belle II detector at the SuperKEKB collider. We achieve an effective tagging efficiency of , where the first uncertainty is statistical and the second systematic, which is 18% better than the previous Belle II algorithm. Demonstrating the algorithm, we use decays to measure the mixing-induced and direct violation parameters, and .
我们提出了一种新算法GFlaT，它使用图神经网络来确定在ϒ(4S)衰变中产生的中性B介子的味道。它利用所有带电终态粒子的信息以及它们之间的关系改进了以前的算法。我们利用在超级KEKB对撞机的Belle II探测器的ϒ(4S)共振中收集到的362 fb-1电子-正电子对撞样本中重建的B衰变到特定味道的强子终态来评估它的性能。我们实现了（37.40±0.43±0.36%）的有效标记效率，其中第一个不确定性是统计不确定性，第二个不确定性是系统不确定性，这比之前的 Belle II 算法提高了 18%。为了演示该算法，我们利用B0→J/ψKS0衰变测量了混合诱导和直接CP违反参数S=(0.724±0.035±0.009)和C=(-0.035±0.026±0.029)。
{"title":"New graph-neural-network flavor tagger for Belle II and measurement of sin 2ϕ1 in B0→J/ψKS0 decays","authors":"I. Adachiet al.(Belle II Collaboration)","doi":"10.1103/physrevd.110.012001","DOIUrl":"https://doi.org/10.1103/physrevd.110.012001","url":null,"abstract":"We present GFlaT, a new algorithm that uses a graph-neural-network to determine the flavor of neutral <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>B</mi></math> mesons produced in <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi mathvariant=\"normal\">ϒ</mi><mo stretchy=\"false\">(</mo><mn>4</mn><mi>S</mi><mo stretchy=\"false\">)</mo></math> decays. It improves previous algorithms by using the information from all charged final-state particles and the relations between them. We evaluate its performance using <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>B</mi></math> decays to flavor-specific hadronic final states reconstructed in a <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mn>362</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> sample of electron-positron collisions collected at the <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi mathvariant=\"normal\">ϒ</mi><mo stretchy=\"false\">(</mo><mn>4</mn><mi>S</mi><mo stretchy=\"false\">)</mo></math> resonance with the Belle II detector at the SuperKEKB collider. We achieve an effective tagging efficiency of <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo stretchy=\"false\">(</mo><mn>37.40</mn><mo>±</mo><mn>0.43</mn><mo>±</mo><mn>0.36</mn><mo>%</mo><mo stretchy=\"false\">)</mo></math>, where the first uncertainty is statistical and the second systematic, which is 18% better than the previous Belle II algorithm. Demonstrating the algorithm, we use <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>B</mi><mn>0</mn></msup><mo stretchy=\"false\">→</mo><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow><msubsup><mi>K</mi><mi mathvariant=\"normal\">S</mi><mn>0</mn></msubsup></math> decays to measure the mixing-induced and direct <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>C</mi><mi>P</mi></math> violation parameters, <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>S</mi><mo>=</mo><mo stretchy=\"false\">(</mo><mn>0.724</mn><mo>±</mo><mn>0.035</mn><mo>±</mo><mn>0.009</mn><mo stretchy=\"false\">)</mo></math> and <math display=\"inline\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>C</mi><mo>=</mo><mo stretchy=\"false\">(</mo><mo>−</mo><mn>0.035</mn><mo>±</mo><mn>0.026</mn><mo>±</mo><mn>0.029</mn><mo stretchy=\"false\">)</mo></math>.","PeriodicalId":20167,"journal":{"name":"Physical Review D","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141495750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1103/physrevb.110.035112
R. Eder, P. Wróbel
We investigate the formation of magnetic polarons in the Kondo lattice model. Calculations are done in the framework of the bond particle formalism. We show that the quasiparticles correspond to spin polarons with a -dependent spatial extent. Polaron formation leads to a significant enhancement of the effective mass in the heavy parts of the band structure.
我们研究了近藤晶格模型中磁极子的形成。计算是在键粒子形式主义框架内完成的。我们证明，准粒子对应于空间范围取决于 k 的自旋极子。极子的形成导致带状结构重元素部分的有效质量显著增强。
{"title":"Magnetic polarons in the Kondo lattice","authors":"R. Eder, P. Wróbel","doi":"10.1103/physrevb.110.035112","DOIUrl":"https://doi.org/10.1103/physrevb.110.035112","url":null,"abstract":"We investigate the formation of magnetic polarons in the Kondo lattice model. Calculations are done in the framework of the bond particle formalism. We show that the quasiparticles correspond to spin polarons with a <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi mathvariant=\"bold\">k</mi></math>-dependent spatial extent. Polaron formation leads to a significant enhancement of the effective mass in the <i>heavy</i> parts of the band structure.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141495852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.3389/fphy.2024.1404236
Jie Song, Lei Chen, Zukun Lu, Baiyu Li, Zhe Liu, Zhihao Xue, Guangfu Sun, Wenhong Liu
Evaluating the computational complexity is critical for assessing the time-domain anti-jamming performance of GNSS receivers. The multiplier is the core component that contributes to the computational complexity in time-domain anti-jamming. However, current algorithms aimed at reducing the complexity of time-domain anti-jamming typically concentrate on shortening the filter length, which fails to address the high computational complexity introduced by the use of multipliers. This paper introduces a cascaded multiplier-free approach for implementing time-domain anti-jamming in navigation receivers. We propose a numerical power decomposition technique based on optimal Canonical Signed Digit coding and coefficient decomposition. By substituting the multiplier with minimal adder and shift operations, the computational complexity of the anti-jamming filter with a high quantization bit-width can be considerably decreased. An optimization strategy is presented, and the low-complexity multiplier-free technique is applied to the time-domain anti-jamming filter. Compared to the traditional Canonical Signed Digit multiplier-free technique, our method can reduce the components required for a 12-bit quantization anti-interference filter by one adder, 20 shift operations, and five coded word lengths, while maintaining a pseudo-range measurement deviation below 0.27 ns.
评估计算复杂度对于评估全球导航卫星系统接收器的时域抗干扰性能至关重要。乘法器是造成时域抗干扰计算复杂性的核心部件。然而，目前旨在降低时域抗干扰复杂度的算法通常集中在缩短滤波器长度上，无法解决使用乘法器带来的高计算复杂度问题。本文介绍了一种在导航接收机中实现时域抗干扰的级联无乘法器方法。我们提出了一种基于最佳 Canonical Signed Digit 编码和系数分解的数值功率分解技术。通过用最小的加法器和移位操作代替乘法器，可以大大降低高量化位宽的抗干扰滤波器的计算复杂度。本文提出了一种优化策略，并将低复杂度无乘法器技术应用于时域抗干扰滤波器。与传统的 Canonical Signed Digit 免乘法器技术相比，我们的方法可以将 12 位量化抗干扰滤波器所需的元件减少一个加法器、20 次移位运算和 5 个编码字长，同时将伪量程测量偏差保持在 0.27 ns 以下。
{"title":"Cascaded multiplier-free implementation of adaptive anti-jamming filter based on GNSS receiver","authors":"Jie Song, Lei Chen, Zukun Lu, Baiyu Li, Zhe Liu, Zhihao Xue, Guangfu Sun, Wenhong Liu","doi":"10.3389/fphy.2024.1404236","DOIUrl":"https://doi.org/10.3389/fphy.2024.1404236","url":null,"abstract":"Evaluating the computational complexity is critical for assessing the time-domain anti-jamming performance of GNSS receivers. The multiplier is the core component that contributes to the computational complexity in time-domain anti-jamming. However, current algorithms aimed at reducing the complexity of time-domain anti-jamming typically concentrate on shortening the filter length, which fails to address the high computational complexity introduced by the use of multipliers. This paper introduces a cascaded multiplier-free approach for implementing time-domain anti-jamming in navigation receivers. We propose a numerical power decomposition technique based on optimal Canonical Signed Digit coding and coefficient decomposition. By substituting the multiplier with minimal adder and shift operations, the computational complexity of the anti-jamming filter with a high quantization bit-width can be considerably decreased. An optimization strategy is presented, and the low-complexity multiplier-free technique is applied to the time-domain anti-jamming filter. Compared to the traditional Canonical Signed Digit multiplier-free technique, our method can reduce the components required for a 12-bit quantization anti-interference filter by one adder, 20 shift operations, and five coded word lengths, while maintaining a pseudo-range measurement deviation below 0.27 ns.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1007/s12648-024-03323-z
Sanjay Kumar
Pandemic from Corona Virus Diseases 2019 (SARS-COVID-19) is a serious hazard to human health and life which is responsible for the significant economic losses across the world. Sometime it resulted into death of human being. Since environmental factors have significant effects on COVID-19 transmission, and vice-versa, therefore lockdown condition which is expected to reduce environmental pollution is an important step to affect COVID transmission through the environment. The associated ambient air pollutant: (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2), and Carbon mono oxide (CO) are directly linked to enhance risk of stroke, heart disease, asthma, and lung cancer and are also affected by the number of cases of COVID-19. In order to have quantitative estimate and comparative study of these pollutants, aerosol optical depth (AOD), surface temperature, ozone, carbon mono oxide (CO) and nitrogen dioxide (NO2), aerosol size distribution over India, have been analysed during lock down period 01 March–30 June, 2020. The analysis of pollutants during lockdown period has been compared to 05 year mean value (2015–2019) estimated during the same period. The satellite based measurement of AOD from MODIS show a decrease in AOD during the lockdown period by 40% in Indian region as compared to 5-year mean level (2015–2019) whereas ground based AOD from AERONET reduced to 75% at Kanpur and 74% at Gandhi College in India. The drop in AOD observed during lockdown is a clear cut indication of reduced level of air pollution. Peak of aerosol size distribution over Kanpur and Gandhi College has also been analysed which show a reduction by 33–50% from the 05-year average level. Enhancement in total ozone column ~ 8% from average level is noticed during the lockdown period which is attributed to suppression in NO2 and CO concentration which is supposed to destroy the formation of ozone through chemical reactions. Influence of lockdown on concentration of environmental pollutants in Indian region has also been compared to top other two countries of the world: USA and Brazil. The pattern of day-to-day variation of COVID cases at India and Brazil is same whereas for USA patterns are significantly different. The comparative analysis of other pollutants between all the three countries has also been discussed and fall in temperature due to lockdown condition over USA is found larger than that over India and Brazil.
{"title":"Effect of lockdown due to COVID-19 on environmental pollutant: a comparative study between top three countries of the world","authors":"Sanjay Kumar","doi":"10.1007/s12648-024-03323-z","DOIUrl":"https://doi.org/10.1007/s12648-024-03323-z","url":null,"abstract":"<p>Pandemic from Corona Virus Diseases 2019 (SARS-COVID-19) is a serious hazard to human health and life which is responsible for the significant economic losses across the world. Sometime it resulted into death of human being. Since environmental factors have significant effects on COVID-19 transmission, and vice-versa, therefore lockdown condition which is expected to reduce environmental pollution is an important step to affect COVID transmission through the environment. The associated ambient air pollutant: (O<sub>3</sub>), nitrogen dioxide (NO<sub>2</sub>), sulphur dioxide (SO<sub>2</sub>), and Carbon mono oxide (CO) are directly linked to enhance risk of stroke, heart disease, asthma, and lung cancer and are also affected by the number of cases of COVID-19. In order to have quantitative estimate and comparative study of these pollutants, aerosol optical depth (AOD), surface temperature, ozone, carbon mono oxide (CO) and nitrogen dioxide (NO<sub>2</sub>), aerosol size distribution over India, have been analysed during lock down period 01 March–30 June, 2020. The analysis of pollutants during lockdown period has been compared to 05 year mean value (2015–2019) estimated during the same period. The satellite based measurement of AOD from MODIS show a decrease in AOD during the lockdown period by 40% in Indian region as compared to 5-year mean level (2015–2019) whereas ground based AOD from AERONET reduced to 75% at Kanpur and 74% at Gandhi College in India. The drop in AOD observed during lockdown is a clear cut indication of reduced level of air pollution. Peak of aerosol size distribution over Kanpur and Gandhi College has also been analysed which show a reduction by 33–50% from the 05-year average level. Enhancement in total ozone column ~ 8% from average level is noticed during the lockdown period which is attributed to suppression in NO<sub>2</sub> and CO concentration which is supposed to destroy the formation of ozone through chemical reactions. Influence of lockdown on concentration of environmental pollutants in Indian region has also been compared to top other two countries of the world: USA and Brazil. The pattern of day-to-day variation of COVID cases at India and Brazil is same whereas for USA patterns are significantly different. The comparative analysis of other pollutants between all the three countries has also been discussed and fall in temperature due to lockdown condition over USA is found larger than that over India and Brazil.</p>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141519174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1103/physreva.110.l011101
V. V. Strelkov, M. A. Khokhlova
We study the phase matching of resonant high-harmonic generation (HHG) and high-order frequency mixing (HFM) in plasma. We numerically solve the propagation equations coupled with the time-dependent Schrödinger equation for the nonlinear polarization. The macroscopic harmonic signal is enhanced in the vicinity of a multiphoton resonance with the transition between the ground and autoionizing states of the generating ion. We show that narrow and strong resonances (as for gallium and indium ions) provide compensation of the plasma dispersion in a spectral region above the exact resonance, improving the phase matching and leading to a high macroscopic signal. The compensation does not take place for a wider resonance (as for manganese ions), instead the phase matching is achieved in the HFM process. Comparing the XUV generated in manganese plasma and in neon gas, we show that the resonant HHG in plasma is an order of magnitude more effective than in the gas; moreover, another order of magnitude can be gained from the propagation using HFM in plasma.
{"title":"Propagation effects in resonant high-order harmonic generation and high-order frequency mixing in a laser plasma","authors":"V. V. Strelkov, M. A. Khokhlova","doi":"10.1103/physreva.110.l011101","DOIUrl":"https://doi.org/10.1103/physreva.110.l011101","url":null,"abstract":"We study the phase matching of resonant high-harmonic generation (HHG) and high-order frequency mixing (HFM) in plasma. We numerically solve the propagation equations coupled with the time-dependent Schrödinger equation for the nonlinear polarization. The macroscopic harmonic signal is enhanced in the vicinity of a multiphoton resonance with the transition between the ground and autoionizing states of the generating ion. We show that narrow and strong resonances (as for gallium and indium ions) provide compensation of the plasma dispersion in a spectral region above the exact resonance, improving the phase matching and leading to a high macroscopic signal. The compensation does not take place for a wider resonance (as for manganese ions), instead the phase matching is achieved in the HFM process. Comparing the XUV generated in manganese plasma and in neon gas, we show that the resonant HHG in plasma is an order of magnitude more effective than in the gas; moreover, another order of magnitude can be gained from the propagation using HFM in plasma.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141514094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1088/1475-7516/2024/07/011
Anish Ghoshal and Alessandro Strumia
We consider an inflationary kinetic function with an integrable pole that is traversed during inflation. This scenario leads to enhanced spectra of primordial scalar inhomogeneities with detectable signals: formation of primordial black holes (that could explain Dark Matter) and scalar-induced gravitational waves (that could reproduce the recent Pulsar Timing Array observation, or predict signals in future detectors such as LISA or ET). Spectral signatures depend on whether the inflaton mass dimension at the pole is above or below 2. Values mildly below 2 allow a big power spectrum enhancement with a mild tuning. Finally, we discuss the possibility that a kinetic pole can arise as anomalous dimension of the inflaton due to quantum effects of Planckian particles that become light at some specific inflaton field value.
我们考虑了具有可积分极点的暴胀动力学函数，该极点在暴胀过程中被穿越。这种情况会导致原始标量不均匀性的光谱增强，从而产生可探测的信号：原始黑洞的形成（可以解释暗物质）和标量诱发的引力波（可以重现最近的脉冲星定时阵列观测，或预测未来探测器（如 LISA 或 ET）的信号）。光谱特征取决于极点处的胀气质量维度是高于还是低于 2。略低于 2 的数值可以通过轻微的调整获得较大的功率谱增强。最后，我们还讨论了一种可能性，即由于普朗克粒子的量子效应，在某些特定的流入子场值下变成光的流入子的反常维度可能会产生动力学极点。
{"title":"Traversing a kinetic pole during inflation: primordial black holes and gravitational waves","authors":"Anish Ghoshal and Alessandro Strumia","doi":"10.1088/1475-7516/2024/07/011","DOIUrl":"https://doi.org/10.1088/1475-7516/2024/07/011","url":null,"abstract":"We consider an inflationary kinetic function with an integrable pole that is traversed during inflation. This scenario leads to enhanced spectra of primordial scalar inhomogeneities with detectable signals: formation of primordial black holes (that could explain Dark Matter) and scalar-induced gravitational waves (that could reproduce the recent Pulsar Timing Array observation, or predict signals in future detectors such as LISA or ET). Spectral signatures depend on whether the inflaton mass dimension at the pole is above or below 2. Values mildly below 2 allow a big power spectrum enhancement with a mild tuning. Finally, we discuss the possibility that a kinetic pole can arise as anomalous dimension of the inflaton due to quantum effects of Planckian particles that become light at some specific inflaton field value.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":null,"pages":null},"PeriodicalIF":6.4,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, we work with lattice Gaussian coding for a K-user Gaussian interference channel. Following the procedure of Etkin et al., in which the capacity is found to be within 1 bit/s/Hz of the capacity of a two-user Gaussian interference channel for each type of interference using random codes, we work with lattices to take advantage of their structure and potential for interference alignment. We mimic random codes using a Gaussian distribution over the lattice. Imposing constraints on the flatness factor of the lattices, the common and private message powers, and the channel coefficients, we find the conditions to obtain the same constant gap to the optimal rate for the two-user weak Gaussian interference channel and the generalized degrees of freedom as those obtained with random codes, as found by Etkin et al. Finally, we show how it is possible to extend these results to a K-user weak Gaussian interference channel using lattice alignment.
在本研究中，我们对 K 用户高斯干扰信道进行格高斯编码。根据 Etkin 等人的研究方法，对于每种干扰类型，使用随机码的容量与双用户高斯干扰信道的容量相差在 1 比特/秒/赫兹以内。我们使用网格上的高斯分布来模拟随机码。通过对网格的平整度系数、公共和私人信息功率以及信道系数施加约束，我们找到了获得双用户弱高斯干扰信道最佳速率恒定差距的条件，以及与埃特金等人使用随机码获得的广义自由度相同的条件。
{"title":"On Superposition Lattice Codes for the K-User Gaussian Interference Channel","authors":"María Constanza Estela, Claudio Valencia-Cordero","doi":"10.3390/e26070575","DOIUrl":"https://doi.org/10.3390/e26070575","url":null,"abstract":"In this study, we work with lattice Gaussian coding for a K-user Gaussian interference channel. Following the procedure of Etkin et al., in which the capacity is found to be within 1 bit/s/Hz of the capacity of a two-user Gaussian interference channel for each type of interference using random codes, we work with lattices to take advantage of their structure and potential for interference alignment. We mimic random codes using a Gaussian distribution over the lattice. Imposing constraints on the flatness factor of the lattices, the common and private message powers, and the channel coefficients, we find the conditions to obtain the same constant gap to the optimal rate for the two-user weak Gaussian interference channel and the generalized degrees of freedom as those obtained with random codes, as found by Etkin et al. Finally, we show how it is possible to extend these results to a K-user weak Gaussian interference channel using lattice alignment.","PeriodicalId":11694,"journal":{"name":"Entropy","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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