Pub Date : 2023-11-09DOI: 10.1103/physreva.108.053707
Jan Petter Hansen, Konrad Tywoniuk
The dynamics of a single quantum state embedded in one continuum or several (quasi)continua is one of the most studied phenomena in quantum mechanics. In this paper we investigate its discrete analog and consider short- and long-time dynamics based on numerical and analytical solutions of the Schr"odinger equation. In addition to derivation of explicit conditions for initial exponential decay, it is shown that a recent model of this class [L. Guo, A. Grimsmo, A. F. Kockum, M. Pletyukhov, and G. Johansson, Phys. Rev. A 95, 053821 (2017)], describing a qubit coupled to a phonon reservoir with energy dependent coupling parameters, is identical to a qubit interacting with a finite number of parallel regularly spaced bands of states via constant couplings. As a consequence, the characteristic near periodic initial-state revivals can be viewed as a transition of probability between different continua via the reviving initial state. Furthermore, polynomial decay of the reviving peaks is present in any system with constant and sufficiently strong coupling.
嵌入在一个连续或几个(准)连续中的单个量子态的动力学是量子力学中研究最多的现象之一。本文基于Schr odinger方程的数值解和解析解研究了它的离散模拟，并考虑了它的短期和长期动力学。除了推导初始指数衰减的显式条件外，还证明了这类最近的一个模型[L]。郭，A. Grimsmo, A. F. Kockum, M. Pletyukhov和G. Johansson，物理学家。[j]，描述了一个量子比特与一个具有能量依赖耦合参数的声子库耦合，与一个量子比特通过恒定耦合与有限数量的平行规则间隔的状态带相互作用相同。因此，近周期初始状态恢复的特征可以看作是通过恢复初始状态在不同连续体之间的概率转移。此外，在任何具有恒定和足够强耦合的系统中，都存在恢复峰的多项式衰减。
{"title":"Decay and revival dynamics of a quantum state embedded in a regularly spaced band of states","authors":"Jan Petter Hansen, Konrad Tywoniuk","doi":"10.1103/physreva.108.053707","DOIUrl":"https://doi.org/10.1103/physreva.108.053707","url":null,"abstract":"The dynamics of a single quantum state embedded in one continuum or several (quasi)continua is one of the most studied phenomena in quantum mechanics. In this paper we investigate its discrete analog and consider short- and long-time dynamics based on numerical and analytical solutions of the Schr\"odinger equation. In addition to derivation of explicit conditions for initial exponential decay, it is shown that a recent model of this class [L. Guo, A. Grimsmo, A. F. Kockum, M. Pletyukhov, and G. Johansson, Phys. Rev. A 95, 053821 (2017)], describing a qubit coupled to a phonon reservoir with energy dependent coupling parameters, is identical to a qubit interacting with a finite number of parallel regularly spaced bands of states via constant couplings. As a consequence, the characteristic near periodic initial-state revivals can be viewed as a transition of probability between different continua via the reviving initial state. Furthermore, polynomial decay of the reviving peaks is present in any system with constant and sufficiently strong coupling.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135241493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-09DOI: 10.1103/physreva.108.053505
You Yu, Zhiqiang Wang, Zhen Fang, Yang Li, Zuxing Zhang
The interplay between the dispersion and spectral filtering effect in Kerr-ring resonators allows the formation of dispersion-less Kerr solitons, an alternative class of Kerr solitons featuring with ultrabroad spectrum and zero chirp. In contrast to a ring resonator, the nonlinear interactions between the counterpropagating light waves in a F-P resonator introduce an additional phase shift, which modifies the system-effective detuning, hence impacting the soliton existence range and its formation dynamics. In this article, we investigate numerically the formation of dissipative Kerr solitons (DKSs) in a 10-mm-long Fabry-P'erot (FP) microresonator with a super-Gaussian spectral filter in the normal dispersion regime. Simulation results found that the spectral loss provided by the filter plays a significant role in the formation of DKS. Without the filter, the FP microresonator yields platicons featuring a flat-top pulse with oscillating tails on both sides. For a super-Gaussian spectral filter with an order of $nensuremath{rightarrow}ensuremath{infty}$, the resonator approaches the transform-limited DKS regime with ultraflat spectrum. An intermediate state of chaotic states of multipulses was observed in the transition from the platicon to the transform-limited DKSs when using the detuning scan technology, the dependence of the appearance of the chaotic state on the spectral filtering effect. Finally, the energy-width scaling behavior and the enhancement of the performances of the transform-limited DKS are studied. Simulation results deepen our understanding of nonlinear dynamics of transform-limited DKS combs and point out a way for achieving a high-energy DKS comb with ultraflat spectrum in Kerr resonators.
克尔环谐振器中色散和光谱滤波效应之间的相互作用允许形成无色散克尔孤子，这是克尔孤子的另一类，具有超远光谱和零啁啾。与环形谐振器相比，F-P谐振器中反向传播光波之间的非线性相互作用引入了额外的相移，这改变了系统有效失谐，从而影响了孤子的存在范围及其形成动力学。在本文中，我们用数值方法研究了在正常色散状态下，具有超高斯谱滤波器的10毫米长的fabry - p (FP)微谐振器中耗散克尔孤子(DKSs)的形成。仿真结果表明，滤波器提供的频谱损耗对DKS的形成起着重要的作用。在没有滤波器的情况下，FP微谐振器产生的脉冲具有平顶脉冲，两侧有振荡尾。对于阶为$nensuremath{rightarrow}ensuremath{infty}$的超高斯谱滤波器，谐振腔接近具有超平坦谱的变换受限DKS区。利用失谐扫描技术，观察到多脉冲在从平台到变换受限dks的过渡过程中存在中间混沌状态，混沌状态的出现与谱滤波效果的关系。最后，研究了变换受限DKS的能量宽度缩放行为和性能的增强。仿真结果加深了我们对变换受限DKS梳的非线性动力学的理解，并为在Kerr谐振器中实现具有超平坦光谱的高能DKS梳指明了一条途径。
{"title":"Transform-limited dissipative Kerr solitons with an ultraflat spectrum in a Fabry-Pérot microresonator with a spectral filter","authors":"You Yu, Zhiqiang Wang, Zhen Fang, Yang Li, Zuxing Zhang","doi":"10.1103/physreva.108.053505","DOIUrl":"https://doi.org/10.1103/physreva.108.053505","url":null,"abstract":"The interplay between the dispersion and spectral filtering effect in Kerr-ring resonators allows the formation of dispersion-less Kerr solitons, an alternative class of Kerr solitons featuring with ultrabroad spectrum and zero chirp. In contrast to a ring resonator, the nonlinear interactions between the counterpropagating light waves in a F-P resonator introduce an additional phase shift, which modifies the system-effective detuning, hence impacting the soliton existence range and its formation dynamics. In this article, we investigate numerically the formation of dissipative Kerr solitons (DKSs) in a 10-mm-long Fabry-P'erot (FP) microresonator with a super-Gaussian spectral filter in the normal dispersion regime. Simulation results found that the spectral loss provided by the filter plays a significant role in the formation of DKS. Without the filter, the FP microresonator yields platicons featuring a flat-top pulse with oscillating tails on both sides. For a super-Gaussian spectral filter with an order of $nensuremath{rightarrow}ensuremath{infty}$, the resonator approaches the transform-limited DKS regime with ultraflat spectrum. An intermediate state of chaotic states of multipulses was observed in the transition from the platicon to the transform-limited DKSs when using the detuning scan technology, the dependence of the appearance of the chaotic state on the spectral filtering effect. Finally, the energy-width scaling behavior and the enhancement of the performances of the transform-limited DKS are studied. Simulation results deepen our understanding of nonlinear dynamics of transform-limited DKS combs and point out a way for achieving a high-energy DKS comb with ultraflat spectrum in Kerr resonators.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135241809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-09DOI: 10.1103/physreva.108.l051102
S. G. Porsev, M. G. Kozlov, M. S. Safronova
An accurate formula for the magnetic-dipole polarizability that takes into account both the positive- and negative-energy-state contributions is presented. The major discrepancy between the theory and experiment is explained.
给出了考虑正能态和负能态贡献的磁偶极子极化率的精确公式。解释了理论与实验之间的主要差异。
{"title":"Contribution of negative-energy states to multipolar polarizabilities of the Sr optical lattice clock","authors":"S. G. Porsev, M. G. Kozlov, M. S. Safronova","doi":"10.1103/physreva.108.l051102","DOIUrl":"https://doi.org/10.1103/physreva.108.l051102","url":null,"abstract":"An accurate formula for the magnetic-dipole polarizability that takes into account both the positive- and negative-energy-state contributions is presented. The major discrepancy between the theory and experiment is explained.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135291414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-09DOI: 10.1103/physreva.108.053110
Johannes K. Krondorfer, Andreas W. Hauser
Nuclear electric resonance (NER) spectroscopy is currently experiencing a revival as a tool for nuclear spin-based quantum computing. Compared to magnetic or electric fields, local electron density fluctuations caused by changes in the atomic environment provide a much higher spatial resolution for the addressing of nuclear spins in qubit registers or within a single molecule. In this article we investigate the possibility of coherent spin control in atoms or molecules via nuclear quadrupole resonance from first principles. An abstract, time-dependent description is provided which entails and reflects on commonly applied approximations. This formalism is then used to propose a method we refer to as ``optical'' nuclear electric resonance (ONER). It employs pulsed optical excitations in the UV-visible light spectrum to modulate the electric field gradient at the position of a specific nucleus of interest by periodic changes of the surrounding electron density. Possible realizations and limitations of ONER for atomically resolved spin manipulation are discussed and tested on $^{9}mathrm{Be}$ as an atomic benchmark system via electronic structure theory.
{"title":"Nuclear electric resonance for spatially resolved spin control via pulsed optical excitation in the UV-visible spectrum","authors":"Johannes K. Krondorfer, Andreas W. Hauser","doi":"10.1103/physreva.108.053110","DOIUrl":"https://doi.org/10.1103/physreva.108.053110","url":null,"abstract":"Nuclear electric resonance (NER) spectroscopy is currently experiencing a revival as a tool for nuclear spin-based quantum computing. Compared to magnetic or electric fields, local electron density fluctuations caused by changes in the atomic environment provide a much higher spatial resolution for the addressing of nuclear spins in qubit registers or within a single molecule. In this article we investigate the possibility of coherent spin control in atoms or molecules via nuclear quadrupole resonance from first principles. An abstract, time-dependent description is provided which entails and reflects on commonly applied approximations. This formalism is then used to propose a method we refer to as ``optical'' nuclear electric resonance (ONER). It employs pulsed optical excitations in the UV-visible light spectrum to modulate the electric field gradient at the position of a specific nucleus of interest by periodic changes of the surrounding electron density. Possible realizations and limitations of ONER for atomically resolved spin manipulation are discussed and tested on $^{9}mathrm{Be}$ as an atomic benchmark system via electronic structure theory.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135241358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-09DOI: 10.1103/physreva.108.052210
Zhi-Xu Zhang, Ji Cao, Wen-Xue Cui, Yu Zhang, Shou Zhang, Hong-Fu Wang
The integration of nonreciprocal non-Hermiticity and topological lattice systems can induce the emergence of the non-Hermitian skin effect, enabling a clear distinction between the behaviors of bulk states in non-Hermitian systems and those in Hermitian systems. Specifically, we focus on examining the localized directions of eigenstates in an odd-sized Su-Schrieffer-Heeger-type lattice with intracell nonreciprocal hopping, and identify a notable phenomenon of detachment between the edge and bulk states, which stands in stark contrast to the behaviors observed in even-sized cases. The localized directions of the bulk and edge states are respectively subjected to the non-Hermitian skin effect and isolated site induced by the odd size of the lattice, resulting in the detachment between the edge and skin states. To provide a comprehensive understanding of the detachment phenomenon, we present analytical solutions that illustrate the localized directions of the edge and skin states whose results are in perfect agreement with the numerical findings. Furthermore, we demonstrate that a pair of eigenstates exhibiting opposite localized directions to the skin states can appear in a trimer non-Hermitian lattice, indicating the possibility of detachment between the edge and skin states in multimer non-Hermitian lattices as well.
{"title":"Detachment between edge and skin states in a non-Hermitian lattice","authors":"Zhi-Xu Zhang, Ji Cao, Wen-Xue Cui, Yu Zhang, Shou Zhang, Hong-Fu Wang","doi":"10.1103/physreva.108.052210","DOIUrl":"https://doi.org/10.1103/physreva.108.052210","url":null,"abstract":"The integration of nonreciprocal non-Hermiticity and topological lattice systems can induce the emergence of the non-Hermitian skin effect, enabling a clear distinction between the behaviors of bulk states in non-Hermitian systems and those in Hermitian systems. Specifically, we focus on examining the localized directions of eigenstates in an odd-sized Su-Schrieffer-Heeger-type lattice with intracell nonreciprocal hopping, and identify a notable phenomenon of detachment between the edge and bulk states, which stands in stark contrast to the behaviors observed in even-sized cases. The localized directions of the bulk and edge states are respectively subjected to the non-Hermitian skin effect and isolated site induced by the odd size of the lattice, resulting in the detachment between the edge and skin states. To provide a comprehensive understanding of the detachment phenomenon, we present analytical solutions that illustrate the localized directions of the edge and skin states whose results are in perfect agreement with the numerical findings. Furthermore, we demonstrate that a pair of eigenstates exhibiting opposite localized directions to the skin states can appear in a trimer non-Hermitian lattice, indicating the possibility of detachment between the edge and skin states in multimer non-Hermitian lattices as well.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135241513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-09DOI: 10.1103/physreve.108.054116
G. Vivek, Debabrata Mondal, S. Sinha
We investigate the nonequilibrium dynamics of a Josephson-coupled Jaynes-Cummings dimer in the presence of Kerr nonlinearity, which can be realized in the cavity and circuit quantum electrodynamics systems. The semiclassical dynamics is analyzed systematically to chart out a variety of photonic Josephson oscillations and their regime of stability. Different types of transitions between the dynamical states lead to the self-trapping phenomenon, which results in photon population imbalance between the two cavities. We also study the dynamics quantum mechanically to identify characteristic features of different steady states and to explore fascinating quantum effects, such as spin dephasing, phase fluctuation, and revival phenomena of the photon field, as well as the entanglement of spin qubits. For a particular ``self-trapped'' state, the mutual information between the atomic qubits exhibits a direct correlation with the photon population imbalance, which is promising for generating photon mediated entanglement between two non interacting qubits in a controlled manner. Under a sudden quench from stable to unstable regime, the photon distribution exhibits phase space mixing with a rapid loss of coherence, resembling a thermal state. Finally, we discuss the relevance of the new results in experiments, which can have applications in quantum information processing and quantum technologies.
{"title":"Nonequilibrium dynamics of the Jaynes-Cummings dimer","authors":"G. Vivek, Debabrata Mondal, S. Sinha","doi":"10.1103/physreve.108.054116","DOIUrl":"https://doi.org/10.1103/physreve.108.054116","url":null,"abstract":"We investigate the nonequilibrium dynamics of a Josephson-coupled Jaynes-Cummings dimer in the presence of Kerr nonlinearity, which can be realized in the cavity and circuit quantum electrodynamics systems. The semiclassical dynamics is analyzed systematically to chart out a variety of photonic Josephson oscillations and their regime of stability. Different types of transitions between the dynamical states lead to the self-trapping phenomenon, which results in photon population imbalance between the two cavities. We also study the dynamics quantum mechanically to identify characteristic features of different steady states and to explore fascinating quantum effects, such as spin dephasing, phase fluctuation, and revival phenomena of the photon field, as well as the entanglement of spin qubits. For a particular ``self-trapped'' state, the mutual information between the atomic qubits exhibits a direct correlation with the photon population imbalance, which is promising for generating photon mediated entanglement between two non interacting qubits in a controlled manner. Under a sudden quench from stable to unstable regime, the photon distribution exhibits phase space mixing with a rapid loss of coherence, resembling a thermal state. Finally, we discuss the relevance of the new results in experiments, which can have applications in quantum information processing and quantum technologies.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135241519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-09DOI: 10.1103/physreva.108.053504
Shiqi Jia, Tong Fu, Jie Peng, Shubo Wang
Optical chirality plays an essential role in chiral light-matter interactions with broad applications in sensing and spectroscopy. Conventional methods of generating optical chirality usually employ chiral structures or chiral excitations. Here, we propose to use an achiral metasurface consisting of a gold disk array excited by a linearly polarized light to generate optical chirality. Using full-wave numerical simulations, we show that the metasurface can give rise to large-area optical chirality of the same sign for a wavelength ranging from 1.2 to $1.5phantom{rule{0.28em}{0ex}}textmu{}mathrm{m}$. The magnitude of the chirality is comparable to that of circularly polarized plane waves. The emergence of optical chirality can be attributed to the asymmetric polarization singularity lines (C lines) in the near fields of the metasurface. We further explore the application of the proposed metasurface in chiral discriminations by simulating the absorption of chiral helix particles immersed in the near fields, and demonstrate that the left-handed and right-handed helix particles give rise to different absorptions. The phenomenon can be understood using an analytical theory based on the dipole approximation, which predicts differential absorption quantitatively agreeing with the numerical simulation results. Our study uncovers the subtle relationship between near-field optical chirality, polarization singularities, and symmetry. The results can find applications in optical sensing, chiral quantum optics, and optical manipulations of small particles.
{"title":"Broadband and large-area optical chirality generated by an achiral metasurface under achiral excitation","authors":"Shiqi Jia, Tong Fu, Jie Peng, Shubo Wang","doi":"10.1103/physreva.108.053504","DOIUrl":"https://doi.org/10.1103/physreva.108.053504","url":null,"abstract":"Optical chirality plays an essential role in chiral light-matter interactions with broad applications in sensing and spectroscopy. Conventional methods of generating optical chirality usually employ chiral structures or chiral excitations. Here, we propose to use an achiral metasurface consisting of a gold disk array excited by a linearly polarized light to generate optical chirality. Using full-wave numerical simulations, we show that the metasurface can give rise to large-area optical chirality of the same sign for a wavelength ranging from 1.2 to $1.5phantom{rule{0.28em}{0ex}}textmu{}mathrm{m}$. The magnitude of the chirality is comparable to that of circularly polarized plane waves. The emergence of optical chirality can be attributed to the asymmetric polarization singularity lines (C lines) in the near fields of the metasurface. We further explore the application of the proposed metasurface in chiral discriminations by simulating the absorption of chiral helix particles immersed in the near fields, and demonstrate that the left-handed and right-handed helix particles give rise to different absorptions. The phenomenon can be understood using an analytical theory based on the dipole approximation, which predicts differential absorption quantitatively agreeing with the numerical simulation results. Our study uncovers the subtle relationship between near-field optical chirality, polarization singularities, and symmetry. The results can find applications in optical sensing, chiral quantum optics, and optical manipulations of small particles.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135290893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-09DOI: 10.1103/physreve.108.054603
Danshi Liu, Jiadong Wang, Xuewei Mao, Jian Deng
The coordinated movement of multiple swimmers is a crucial component of fish schools. Fish swimming in different formations, such as tandem, side-by-side, diamond, and phalanx, can achieve significant energetic advantages. However, the energetic benefits of nonstraight swimming behaviors, such as the collective motion of a milling pattern, are not well understood. To fill in this gap, we consider two swimmers in circular tracks, controlled by a PID approach to reach stable configurations. Our study finds that the optimal phase is affected by circumferential effects, and that substantial energy savings can result from both propulsion and turning. We also explore the radial effect in terms of energetic benefits. In a milling pattern, the inner swimmers can easily gain a certain energetic benefit ($ensuremath{-}8%$), while their peers on the outside must be close enough to the inner swimmer with a proper phase to gain the energetic benefit ($ensuremath{-}14%$). When the radial spacing becomes larger or is in an unmatched phase, the swimming of the outer swimmers becomes more laborious ($+16%$). Our results indicate that swimmers who maintain a matched phase and minimum radial effect obtain the highest energetic benefits ($ensuremath{-}26%$). These findings highlight the energetic benefits of swimmers, even in a milling pattern, where the position difference dominates the extent of benefit.
{"title":"Energetic benefits in coordinated circular swimming motion of two swimmers","authors":"Danshi Liu, Jiadong Wang, Xuewei Mao, Jian Deng","doi":"10.1103/physreve.108.054603","DOIUrl":"https://doi.org/10.1103/physreve.108.054603","url":null,"abstract":"The coordinated movement of multiple swimmers is a crucial component of fish schools. Fish swimming in different formations, such as tandem, side-by-side, diamond, and phalanx, can achieve significant energetic advantages. However, the energetic benefits of nonstraight swimming behaviors, such as the collective motion of a milling pattern, are not well understood. To fill in this gap, we consider two swimmers in circular tracks, controlled by a PID approach to reach stable configurations. Our study finds that the optimal phase is affected by circumferential effects, and that substantial energy savings can result from both propulsion and turning. We also explore the radial effect in terms of energetic benefits. In a milling pattern, the inner swimmers can easily gain a certain energetic benefit ($ensuremath{-}8%$), while their peers on the outside must be close enough to the inner swimmer with a proper phase to gain the energetic benefit ($ensuremath{-}14%$). When the radial spacing becomes larger or is in an unmatched phase, the swimming of the outer swimmers becomes more laborious ($+16%$). Our results indicate that swimmers who maintain a matched phase and minimum radial effect obtain the highest energetic benefits ($ensuremath{-}26%$). These findings highlight the energetic benefits of swimmers, even in a milling pattern, where the position difference dominates the extent of benefit.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135291158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The authors theoretically investigate the impact of Dirac negative-energy states on the $E$2 and $M$1 polarizabilities in optical clocks. They demonstrate the importance of negative-energy states for the $M$1 polarizability and resolve the sign inconsistency between the theoretical calculations and experimental measurements in the $E$2-$M$1 polarizability difference of the Sr clock.
{"title":"Contribution of negative-energy states to the E2−M1 polarizability of optical clocks","authors":"Fang-Fei Wu, Ting-Yun Shi, Wei-Tou Ni, Li-Yan Tang","doi":"10.1103/physreva.108.l051101","DOIUrl":"https://doi.org/10.1103/physreva.108.l051101","url":null,"abstract":"The authors theoretically investigate the impact of Dirac negative-energy states on the $E$2 and $M$1 polarizabilities in optical clocks. They demonstrate the importance of negative-energy states for the $M$1 polarizability and resolve the sign inconsistency between the theoretical calculations and experimental measurements in the $E$2-$M$1 polarizability difference of the Sr clock.","PeriodicalId":20121,"journal":{"name":"Physical Review","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135241510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-09DOI: 10.1103/physreva.108.052809
C. T. Plowman, K. H. Spicer, M. Schulz, A. S. Kadyrov
The wave-packet convergent close-coupling (WP-CCC) approach is applied to calculate the energy spectrum of electrons ejected in $p+{mathrm{H}}_{2}$ collisions as a function of the scattering angle of the projectile. The calculations are performed for projectile energies of 75, 100, and 200 keV. At these incident energies there are many competing reaction channels that play an essential role in the collision dynamics. The target is modeled as an orientationally averaged effective one-electron system. The results are compared with available perturbative calculations and experimental data. Good agreement between the WP-CCC results and experimental data is found for small emission energies, especially when the projectile is scattered at small angles. However, when the electron is emitted with a speed comparable to or greater than the projectile speed we find that our method predicts smaller cross sections near zero scattering angles and a slower fall off than the experimental data. This is in agreement with other calculations. Furthermore, the structure observed in the experimental data at large scattering angles is not supported by our results. Interestingly, we find very good agreement with the continuum-distorted-wave eikonal-initial-state molecular-orbital calculations that use a two-effective center approximation, though our method describes the target as an effective one-electron spherically symmetric system. This suggests that in these models two-center interference effects may have a small effect on this particular cross section. Furthermore, we find that the experimentally observed decrease in average scattering angle in proton collisions with ${mathrm{H}}_{2}$ near the electron-projectile matching speed is not reproduced by our results. We also present the doubly differential cross section for ionization as a function of the scattering angle of the projectile at select emission angles.
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