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Journal of Physics B最新文献

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Motion of a condensate in a shaken and vibrating harmonic trap 振荡和振动谐波阱中凝结水的运动
Journal of Physics B Pub Date : 2002-04-14 DOI: 10.1088/0953-4075/35/10/315
Y. Japha, Y. Band
{"title":"Motion of a condensate in a shaken and vibrating harmonic trap","authors":"Y. Japha, Y. Band","doi":"10.1088/0953-4075/35/10/315","DOIUrl":"https://doi.org/10.1088/0953-4075/35/10/315","url":null,"abstract":"The dynamics of a Bose-Einstein condensate (BEC) in a time-dependent harmonic trapping potential is determined for arbitrary variations of the position of the centre of the trap and its frequencies. The dynamics of the BEC wavepacket is soliton-like. The motion of the centre of the wavepacket, and the spatially and temporally dependent phase (which affects the coherence properties of the BEC) multiplying the soliton-like part of the wavepacket, are analytically determined.","PeriodicalId":16799,"journal":{"name":"Journal of Physics B","volume":"88 1","pages":"2383-2389"},"PeriodicalIF":0.0,"publicationDate":"2002-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84281124","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}
引用次数: 12
Electron magnetic resonance: the modified Bloch equation 电子磁共振:修正的布洛赫方程
Journal of Physics B Pub Date : 2002-02-13 DOI: 10.1088/0953-4075/35/4/330
B. Segev, Y. Band, Y. Band
{"title":"Electron magnetic resonance: the modified Bloch equation","authors":"B. Segev, Y. Band, Y. Band","doi":"10.1088/0953-4075/35/4/330","DOIUrl":"https://doi.org/10.1088/0953-4075/35/4/330","url":null,"abstract":"We find a modified Bloch equation for the electronic magnetic moment when the magnetic moment explicitly contains a diamagnetic contribution (a magnetic-field-induced magnetic moment arising from the electronic orbital angular momentum) in addition to the intrinsic magnetic moment of the electron. The modified Bloch equation is coupled to equations of motion for the position and momentum operators. In the presence of static and time varying magnetic field components, the magnetic moment oscillates out of phase with the magnetic field and power is absorbed by virtue of the magnetic-field-induced magnetic moment, even in the absence of coupling to the environment. We explicitly work out the spectrum and absorption for the case of a p state electron.","PeriodicalId":16799,"journal":{"name":"Journal of Physics B","volume":"38 1","pages":"1085-1094"},"PeriodicalIF":0.0,"publicationDate":"2002-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84854522","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}
引用次数: 0
Bose-Einstein condensation on inhomogeneous complex networks 非齐次复杂网络上的玻色-爱因斯坦凝聚
Journal of Physics B Pub Date : 2001-12-14 DOI: 10.1088/0953-4075/34/23/314
R. Burioni, D. Cassi, M. Rasetti, Pasquale Sodano, A. Vezzani
{"title":"Bose-Einstein condensation on inhomogeneous complex networks","authors":"R. Burioni, D. Cassi, M. Rasetti, Pasquale Sodano, A. Vezzani","doi":"10.1088/0953-4075/34/23/314","DOIUrl":"https://doi.org/10.1088/0953-4075/34/23/314","url":null,"abstract":"The thermodynamic properties of non-interacting bosons on a complex network can be strongly affected by topological inhomogeneities. The latter give rise to anomalies in the density of states that can induce Bose-Einstein condensation (BEC) in low-dimensional systems also in the absence of external confining potentials. The anomalies consist of energy regions composed of an infinite number of states with vanishing weight in the thermodynamic limit. We present a rigorous result providing the general conditions for the occurrence of BEC on complex networks in the presence of anomalous spectral regions in the density of states. We present results on spectral properties for a wide class of graphs where the theorem applies. We study in detail an explicit geometrical realization, the comb lattice, which embodies all the relevant features of this effect and which can be experimentally implemented as an array of Josephson junctions.","PeriodicalId":16799,"journal":{"name":"Journal of Physics B","volume":"14 1","pages":"4697-4710"},"PeriodicalIF":0.0,"publicationDate":"2001-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82221856","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}
引用次数: 69
A quasiclassical approach to electron impact ionization 电子冲击电离的准经典方法
Journal of Physics B Pub Date : 2001-10-28 DOI: 10.1088/0953-4075/35/6/306
T. Geyer, J. Rost
{"title":"A quasiclassical approach to electron impact ionization","authors":"T. Geyer, J. Rost","doi":"10.1088/0953-4075/35/6/306","DOIUrl":"https://doi.org/10.1088/0953-4075/35/6/306","url":null,"abstract":"A quasiclassical approximation to quantum mechanical scattering in the Moller formalism is developed. While keeping the numerical advantage of a standard classical trajectory Monte Carlo calculation, our approach is no longer restricted to using stationary initial distributions. This allows one to improve the results by using better suited initial phase space distributions than the microcanonical one and to gain insight into the collision mechanism by studying the influence of different initial distributions on the cross section. A comprehensive account of results for single, double and triple differential cross sections for atomic hydrogen will be given, in comparison with experiment and other theories.","PeriodicalId":16799,"journal":{"name":"Journal of Physics B","volume":"14 1","pages":"1479-1499"},"PeriodicalIF":0.0,"publicationDate":"2001-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90204865","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}
引用次数: 12
Explicitly correlated trial wavefunctions in quantum Monte Carlo calculations of excited states of Be and Be 量子蒙特卡罗计算中Be和Be激发态的显式相关试验波函数
Journal of Physics B Pub Date : 2000-11-22 DOI: 10.1088/0953-4075/34/3/304
L. Bertini, D. Bressanini, M. Mella, G. Morosi
{"title":"Explicitly correlated trial wavefunctions in quantum Monte Carlo calculations of excited states of Be and Be","authors":"L. Bertini, D. Bressanini, M. Mella, G. Morosi","doi":"10.1088/0953-4075/34/3/304","DOIUrl":"https://doi.org/10.1088/0953-4075/34/3/304","url":null,"abstract":"We present a new form of explicitly correlated wavefunction whose parameters are mainly linear, to circumvent the problem of the optimization of a large number of nonlinear parameters usually encountered with basis sets of explicitly correlated wavefunctions. With this trial wavefunction we have succeeded in minimizing the energy instead of the variance of the local energy, as is more common in quantum Monte Carlo methods. We have applied this wavefunction to the calculation of the energies of Be 3 P (1s 2 2p 2 ) and Be − 4 S o (1s 2 2p 3 ) by variational and diffusion Monte Carlo methods. The results compare favourably with those obtained by different types of explicitly correlated trial wavefunction already described in the literature. The energies obtained are improved with respect to the best variational ones found in the literature, and within one standard deviation of the estimated non-relativistic limits.","PeriodicalId":16799,"journal":{"name":"Journal of Physics B","volume":"35 1","pages":"257-266"},"PeriodicalIF":0.0,"publicationDate":"2000-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90185500","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}
引用次数: 13
Reverse dark resonance in Rb excited by a diode laser 二极管激光激发Rb中的反向暗共振
Journal of Physics B Pub Date : 2000-11-21 DOI: 10.1088/0953-4075/34/20/302
J. Alnis, M. Auzinsh
{"title":"Reverse dark resonance in Rb excited by a diode laser","authors":"J. Alnis, M. Auzinsh","doi":"10.1088/0953-4075/34/20/302","DOIUrl":"https://doi.org/10.1088/0953-4075/34/20/302","url":null,"abstract":"The origin of recently discovered reverse (opposite-sign) dark resonances has been explained theoretically and verified experimentally. It is shown that the reason for these resonances is a specific optical pumping of the ground state magnetic sublevel in a transition when the ground state angular momentum is smaller than the excited state momentum. An experiment was conducted on 85Rb atoms in a cell, when a diode laser using the ground state hyperfine level Fg = 3 simultaneously excites spectrally unresolved hyperfine levels with total angular momentum quantum numbers Fe = 2,3 and 4. It is shown that due to differences in the transition probabilities the dominant role in total absorption and fluorescence signals is played by absorption on a transition Fg = 3→Fe = 4.","PeriodicalId":16799,"journal":{"name":"Journal of Physics B","volume":"23 1","pages":"3889-3898"},"PeriodicalIF":0.0,"publicationDate":"2000-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74459818","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}
引用次数: 11
Electron-impact excitation of argon: II. The lowest resonance 4s[3/2]1 and metastable 4s[3/2]2 and 4s'[½]0 states 氩的电子冲击激发:2。最低共振态4s[3/2]1和亚稳态4s[3/2]2和4s'[½]0
Journal of Physics B Pub Date : 2000-06-14 DOI: 10.1088/0953-4075/33/11/308
D. Filipović, B. Marinković, V. Pejčev, L. Vŭsković
{"title":"Electron-impact excitation of argon: II. The lowest resonance 4s[3/2]1 and metastable 4s[3/2]2 and 4s'[½]0 states","authors":"D. Filipović, B. Marinković, V. Pejčev, L. Vŭsković","doi":"10.1088/0953-4075/33/11/308","DOIUrl":"https://doi.org/10.1088/0953-4075/33/11/308","url":null,"abstract":"Absolute normalized differential electron-impact excitation cross sections (DCSs) are presented for the lowest three electronic states of argon: the lowest resonance 4s[3/2]1 (1s4 in Paschen's notation) state and two neighbouring metastable 4s[3/2]2 and 4s'[½]0 (1s5 and 1s3 in Paschen's notation) states. Direct, i.e. free of a cascade contribution, excitation cross sections were obtained experimentally for the 4s[3/2]1 state at 20, 40, 50 and 80 eV and for the 4s[3/2]2 and 4s'[½]0 states at 20 and 40 eV impact energies. The measurements were performed at scattering angles between 5° and 150° with an angular resolution of better than 2°. The ratios: r = DCS(4s[3/2]2)/DCS(4s'[½]0) and r' = DCS(4s[3/2]1)/DCS(4s'[½]1) were determined and compared with other available experimental and theoretical results. The absolute DCS scale was established with respect to DCSs of the 4s'[½]1 state (Filipovic et al 2000 J. Phys. B: At. Mol. Opt. Phys. 33 677) using the peak intensity ratios in the energy-loss spectra. The DCSs were extrapolated to 0° and 180° and numerically integrated to yield integral, momentum transfer and viscosity cross sections.","PeriodicalId":16799,"journal":{"name":"Journal of Physics B","volume":"474 1","pages":"2081-2094"},"PeriodicalIF":0.0,"publicationDate":"2000-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77048296","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}
引用次数: 19
Relativistic many-body calculations of transition probabilities for the 2l12l2[LSJ]-2l33l4[L´S´J´] lines in Be-like ions 类贝离子中2l12l2[LSJ]-2l33l4[L´S´J]谱线跃迁概率的相对论多体计算
Journal of Physics B Pub Date : 1999-07-28 DOI: 10.1088/0953-4075/32/14/319
U. Safronova, A. Derevianko, M. Safronova, W. Johnson
{"title":"Relativistic many-body calculations of transition probabilities for the 2l12l2[LSJ]-2l33l4[L´S´J´] lines in Be-like ions","authors":"U. Safronova, A. Derevianko, M. Safronova, W. Johnson","doi":"10.1088/0953-4075/32/14/319","DOIUrl":"https://doi.org/10.1088/0953-4075/32/14/319","url":null,"abstract":"Reduced matrix elements, oscillator strengths, and transition rates are calculated for 2l12l2[LSJ]-2l33l4[L´S´J´] electric-dipole transitions in beryllium-like ions with nuclear charges Z from 6 to 100. Many-body perturbation theory (MBPT), including the Breit interaction, is used to evaluate retarded dipole matrix elements in length and velocity forms. The calculations start with a 1s2 Dirac-Fock potential and include all possible n = 2 and n = 3 configurations. We use first-order perturbation theory to obtain intermediate coupling coefficients and second-order MBPT to determine matrix elements. The transition energies used to evaluate transition probabilities are also obtained from second-order MBPT. The importance of negative-energy contributions to the transition amplitudes in maintaining gauge independence is discussed. Our results for 2s3p 1,3P1-2s2 1S0 transitions are compared with available theoretical and experimental data throughout the isoelectronic sequence. Rates for 2l3l´ [J = 1]-2s2 1S0, 2l3l´ [J = 1]-2p2 1S2, 2l3l´ [J = 1]-2s2p 1P1, and 2l3l´ [J = 2]-2s2p 1P1 transitions are given graphically for all Z.","PeriodicalId":16799,"journal":{"name":"Journal of Physics B","volume":"22 1","pages":"3527-3545"},"PeriodicalIF":0.0,"publicationDate":"1999-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72692637","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}
引用次数: 39
Geometry and symmetries of multi-particle systems 多粒子系统的几何和对称性
Journal of Physics B Pub Date : 1999-03-28 DOI: 10.1088/0953-4075/32/6/004
U. Fano, D. Green, J. Bohn, T. Heim
{"title":"Geometry and symmetries of multi-particle systems","authors":"U. Fano, D. Green, J. Bohn, T. Heim","doi":"10.1088/0953-4075/32/6/004","DOIUrl":"https://doi.org/10.1088/0953-4075/32/6/004","url":null,"abstract":"The quantum dynamical evolution of atomic and molecular aggregates, from their compact to their fragmented states, is parametrized by a single collective radial parameter. Treating all the remaining particle coordinates in d dimensions democratically, as a set of angles orthogonal to this collective radius or by equivalent variables, bypasses all independent-particle approximations. The invariance of the total kinetic energy under arbitrary d-dimensional transformations which preserve the radial parameter gives rise to novel quantum numbers and ladder operators interconnecting its eigenstates at each value of the radial parameter. We develop the systematics and technology of this approach, introducing the relevant mathematics tutorially, by analogy to the familiar theory of angular momentum in three dimensions. The angular basis functions so obtained are treated in a manifestly coordinate-free manner, thus serving as a flexible generalized basis for carrying out detailed studies of wavefunction evolution in multi-particle systems.","PeriodicalId":16799,"journal":{"name":"Journal of Physics B","volume":"63 2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1999-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83750237","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}
引用次数: 26
Electron impact excitation of the states of Ar , Kr and Xe atoms Ar, Kr和Xe原子态的电子冲击激发
Journal of Physics B Pub Date : 1998-11-14 DOI: 10.1088/0953-4075/31/21/015
S. Kaur, R. Srivastava, R. McEachran, A. Stauffer
{"title":"Electron impact excitation of the states of Ar , Kr and Xe atoms","authors":"S. Kaur, R. Srivastava, R. McEachran, A. Stauffer","doi":"10.1088/0953-4075/31/21/015","DOIUrl":"https://doi.org/10.1088/0953-4075/31/21/015","url":null,"abstract":"Electron impact excitation of all the and 3 states of argon (n = 3), krypton (n = 4) and xenon (n = 5) from the ground state has been considered in the relativistic distorted-wave approximation. The differential and total cross sections are obtained for incident electrons in the energy range from 15 to 100 eV. The results are compared with the available experimental data and a few theoretical non-relativistic and semi-relativistic calculations wherever possible.","PeriodicalId":16799,"journal":{"name":"Journal of Physics B","volume":"25 1","pages":"4833-4852"},"PeriodicalIF":0.0,"publicationDate":"1998-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78875787","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}
引用次数: 21
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