Pub Date : 1999-08-01DOI: 10.1088/1004-423X/8/8/005
Deng Le, Wang Wei-sheng, Sun Zhen-rong, Ding Liang-en, Wang Zu-geng
Population trapping via quantum interference in a multi-level system driven by a coherent field is investigated. The influences of the alignment of the transition dipole moments and the energy-level separation of the upper levels are taken into account. Detailed trapping population profiles under the different conditions are given. The research result is helpful for simplifying the theoretical model and selecting rational energy level system.
{"title":"Population trapping in multi-level system via quantum interference","authors":"Deng Le, Wang Wei-sheng, Sun Zhen-rong, Ding Liang-en, Wang Zu-geng","doi":"10.1088/1004-423X/8/8/005","DOIUrl":"https://doi.org/10.1088/1004-423X/8/8/005","url":null,"abstract":"Population trapping via quantum interference in a multi-level system driven by a coherent field is investigated. The influences of the alignment of the transition dipole moments and the energy-level separation of the upper levels are taken into account. Detailed trapping population profiles under the different conditions are given. The research result is helpful for simplifying the theoretical model and selecting rational energy level system.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132185044","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 : 1999-08-01DOI: 10.1088/1004-423X/8/8/007
P. Xiao-feng, Li Ping
Effects of the nonadiabatic phonon fluctuations on the ground state of coupled one-dimensional electron-phonon systems with high and low electron-densities were investigated by a new ansatz including correlated interaction of the displacement and squeezing. The correlated effect resulted in noticeable reduction of ground state energy of the systems, and obvious increases of binding energy of the polarons occurred. Thus, the stabilities of the polaron and of the systems were significantly enhanced, exactly steady ground state of the Holstein model, then, was obtained by the new ansatz for the coupled electron-phonon systems. In general, the new ansatz were found to be very relevant for the strong coupling and large squeezing cases in nonadiabatically coupled electron-photon systems.
{"title":"The properties of the ground state of the nonadiabatically coupled electron-phonon systems with correlated displacement and squeezing","authors":"P. Xiao-feng, Li Ping","doi":"10.1088/1004-423X/8/8/007","DOIUrl":"https://doi.org/10.1088/1004-423X/8/8/007","url":null,"abstract":"Effects of the nonadiabatic phonon fluctuations on the ground state of coupled one-dimensional electron-phonon systems with high and low electron-densities were investigated by a new ansatz including correlated interaction of the displacement and squeezing. The correlated effect resulted in noticeable reduction of ground state energy of the systems, and obvious increases of binding energy of the polarons occurred. Thus, the stabilities of the polaron and of the systems were significantly enhanced, exactly steady ground state of the Holstein model, then, was obtained by the new ansatz for the coupled electron-phonon systems. In general, the new ansatz were found to be very relevant for the strong coupling and large squeezing cases in nonadiabatically coupled electron-photon systems.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114019115","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 : 1999-08-01DOI: 10.1088/1004-423X/8/8/009
Hu Liang-bin, Li Hai-jin, Tao Rui-bao
A lattice model is proposed to describe the stripe domain structure in a magnetic ultrathin film that consists of only a few or tens of monolayers and has a perpendicular anisotropy. The dipolar energies of the perpendicular and in-plane uniform magnetic states and the stripe domain structures in a magnetic ultrathin film are calculated separately using Ewald's lattice summation method. The thickness dependence of the stripe domain structure is investigated, and the stability of the stripe domain structure is discussed. The results show that for magnetic ultrathin films the stripe domain structure may have very sensitive dependence on their thickness.
{"title":"Lattice model of stripe domain structure in ferromagnetic ultrathin films","authors":"Hu Liang-bin, Li Hai-jin, Tao Rui-bao","doi":"10.1088/1004-423X/8/8/009","DOIUrl":"https://doi.org/10.1088/1004-423X/8/8/009","url":null,"abstract":"A lattice model is proposed to describe the stripe domain structure in a magnetic ultrathin film that consists of only a few or tens of monolayers and has a perpendicular anisotropy. The dipolar energies of the perpendicular and in-plane uniform magnetic states and the stripe domain structures in a magnetic ultrathin film are calculated separately using Ewald's lattice summation method. The thickness dependence of the stripe domain structure is investigated, and the stability of the stripe domain structure is discussed. The results show that for magnetic ultrathin films the stripe domain structure may have very sensitive dependence on their thickness.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125209074","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 : 1999-08-01DOI: 10.1088/1004-423X/8/8/002
Wang Tieshan, K. Ochiai, Kathohiko Maruta, A. Takahashi
Atomic and nuclear cluster effects of (D3+) were studied by alternative implantation of deuterium cluster ion beam and isolated deuteron (D+) beam on metal targets. The beam energy was adjusted from 10 keV/d to 100 keV/d in experiment. The atomic cluster effect was shown by the enhancement of x-ray emission induced by cluster deuteron. The average ratio of x-ray intensity induced by each cluster deuteron to that induced by each isolated deuteron is about 2.6 in the experimental energy region. The nuclear cluster effect is shown by the difference of D-D fusion rates induced by two kinds of deuterons under the same experimental conditions. The ratio of the D-D fusion rates induced by the two kinds of deuterons is energy dependent.
{"title":"CLUSTER EFFECTS IN DEUTERIUM CLUSTER ION IMPLANTATION ON SOLIDS","authors":"Wang Tieshan, K. Ochiai, Kathohiko Maruta, A. Takahashi","doi":"10.1088/1004-423X/8/8/002","DOIUrl":"https://doi.org/10.1088/1004-423X/8/8/002","url":null,"abstract":"Atomic and nuclear cluster effects of (D3+) were studied by alternative implantation of deuterium cluster ion beam and isolated deuteron (D+) beam on metal targets. The beam energy was adjusted from 10 keV/d to 100 keV/d in experiment. The atomic cluster effect was shown by the enhancement of x-ray emission induced by cluster deuteron. The average ratio of x-ray intensity induced by each cluster deuteron to that induced by each isolated deuteron is about 2.6 in the experimental energy region. The nuclear cluster effect is shown by the difference of D-D fusion rates induced by two kinds of deuterons under the same experimental conditions. The ratio of the D-D fusion rates induced by the two kinds of deuterons is energy dependent.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128146585","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 : 1999-08-01DOI: 10.1088/1004-423X/8/8/004
Lu Hong, Guo Guangcan
The two-mode photon-added state defined by |?, q; m>?=?a+mb+m|?, q> up to a normalization constant is introduced, where |?, q> is a pair coherent state and m an integer. It is shown that the fields in such a state have remarkable quantum features such as sub-Poissonian statistics, violations of Cauch-Schwarz inequalities, correlations in the number fluctuations and squeezing. We examine the influence of photon-adding on the properties of pair coherent state, and propose a method of generating two-mode photon-added states in the context of cavity quantum electrodynamics.
{"title":"NONCLASSICAL PROPERTIES OF PHOTON-ADDED PAIR COHERENT STATES","authors":"Lu Hong, Guo Guangcan","doi":"10.1088/1004-423X/8/8/004","DOIUrl":"https://doi.org/10.1088/1004-423X/8/8/004","url":null,"abstract":"The two-mode photon-added state defined by |?, q; m>?=?a+mb+m|?, q> up to a normalization constant is introduced, where |?, q> is a pair coherent state and m an integer. It is shown that the fields in such a state have remarkable quantum features such as sub-Poissonian statistics, violations of Cauch-Schwarz inequalities, correlations in the number fluctuations and squeezing. We examine the influence of photon-adding on the properties of pair coherent state, and propose a method of generating two-mode photon-added states in the context of cavity quantum electrodynamics.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"243 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134085299","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 : 1999-08-01DOI: 10.1088/1004-423X/8/8/008
Chen Xueyuan, Luo Zundu
Based on the analysis of group-chain scheme, the crystal-field-level fitting of Nd3+:LiYF4 has been carried out, in which the Nd3+ ions occupy positions with site symmetry S4. The RMS deviation of energy-level fitting is 12.8 cm-1. Using the obtained wave functions, g-factors of the ground state are calculated, which are g||?=?2.067 and g??=?2.631, in good agreement with the experimental values (g|| = 1.987 and g??=?2.554). The method proposed turns out to be effective in the study of spectral properties of localized centres in laser crystals.
{"title":"GROUP-CHAIN SCHEME ANALYSIS OF THE ENERGY LEVELS AND MAGNETIC PROPERTIES OF Nd 3+ IN LiYF 4 CRYSTAL","authors":"Chen Xueyuan, Luo Zundu","doi":"10.1088/1004-423X/8/8/008","DOIUrl":"https://doi.org/10.1088/1004-423X/8/8/008","url":null,"abstract":"Based on the analysis of group-chain scheme, the crystal-field-level fitting of Nd3+:LiYF4 has been carried out, in which the Nd3+ ions occupy positions with site symmetry S4. The RMS deviation of energy-level fitting is 12.8 cm-1. Using the obtained wave functions, g-factors of the ground state are calculated, which are g||?=?2.067 and g??=?2.631, in good agreement with the experimental values (g|| = 1.987 and g??=?2.554). The method proposed turns out to be effective in the study of spectral properties of localized centres in laser crystals.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134245864","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 : 1999-07-20DOI: 10.1088/1004-423X/8/7/005
W. Nan, Xie Wen-jun, Wei Bingbo
Electromagnetic levitation has developed from a pure physical phenomenon into a practical containerless processing technique in the fields of both applied physics and materials science. In order to obtain a better understanding of this processing technique, two typical levitation coils were designed and the physical characteristics in levitation droplets suspended in these two coils, such as electromangetic field, levitation force field, total levitation force, and power absorption, were analyzed numerically and calculated in this paper. It was found that the eddy current density, together with the magnetic flux density and levitation force density, increases rapidly with radius as it approaches sample surface. The maximum levitation force produced by coil A is larger than that of coil B, whereas the levitated sample can obtain less power absorption at the equilibrium position in the former coil than that in the latter one. Moreover, the calculated results also demonstrated that the levitation ability decreases as the atomic number increases. The larger the material’s electrical resistivity, the easier the samples can obtain more power absorption. PACC: 4110F; 1220; 6470D; 0260
{"title":"Physical characteristics of electromagnetic levitation processing","authors":"W. Nan, Xie Wen-jun, Wei Bingbo","doi":"10.1088/1004-423X/8/7/005","DOIUrl":"https://doi.org/10.1088/1004-423X/8/7/005","url":null,"abstract":"Electromagnetic levitation has developed from a pure physical phenomenon into a practical containerless processing technique in the fields of both applied physics and materials science. In order to obtain a better understanding of this processing technique, two typical levitation coils were designed and the physical characteristics in levitation droplets suspended in these two coils, such as electromangetic field, levitation force field, total levitation force, and power absorption, were analyzed numerically and calculated in this paper. It was found that the eddy current density, together with the magnetic flux density and levitation force density, increases rapidly with radius as it approaches sample surface. The maximum levitation force produced by coil A is larger than that of coil B, whereas the levitated sample can obtain less power absorption at the equilibrium position in the former coil than that in the latter one. Moreover, the calculated results also demonstrated that the levitation ability decreases as the atomic number increases. The larger the material’s electrical resistivity, the easier the samples can obtain more power absorption. PACC: 4110F; 1220; 6470D; 0260","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124668703","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 : 1999-07-20DOI: 10.1088/1004-423X/8/7/004
Zhang Sui-meng, Chen Zhang-jin
Following the work of Berakdar, the momentum correlation in the three-body Coulomb continuum problem is considered by the introduction of effective Sommerfeld parameters for both symmetric and asymmetric geometry. The triple differential cross sections for electron impact ionization of atomic hydrogen at incident energies of 54.4 and 150eV in asymmetric geometry are calculated. Results are compared with the related measurements and the only existing theoretical results of the convergent close-coupling method. They are in good agreement with experiment, though some small quantitative discrepancies remain.
{"title":"Momentum correlation of electron-hydrogen ionization","authors":"Zhang Sui-meng, Chen Zhang-jin","doi":"10.1088/1004-423X/8/7/004","DOIUrl":"https://doi.org/10.1088/1004-423X/8/7/004","url":null,"abstract":"Following the work of Berakdar, the momentum correlation in the three-body Coulomb continuum problem is considered by the introduction of effective Sommerfeld parameters for both symmetric and asymmetric geometry. The triple differential cross sections for electron impact ionization of atomic hydrogen at incident energies of 54.4 and 150eV in asymmetric geometry are calculated. Results are compared with the related measurements and the only existing theoretical results of the convergent close-coupling method. They are in good agreement with experiment, though some small quantitative discrepancies remain.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123040507","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 : 1999-07-20DOI: 10.1088/1004-423X/8/7/010
Wang Yuan-fei, Han Bao-shan
Experiments were statistically carried out on the behavior of vertical-Bloch-line (VBL) chains in the walls of the second kind of dumbbell domains (IIDs) is garnet bubble films subjected to joint action of static bias field H-b and in-plane field H-ip. The curves of the four critical in-plane fields, (H-ip)(IID-ID) (Hip)(IID-OHB) (Hip)(IID-SB) and H-ip' vs H-b were measured and explained. In particular, in terms of two series of IID photos, a new experimental manifestation of the unknown "number effect" of VBL chains was found.
{"title":"Annihilation of vertical-bloch-line chains in the walls of the second kind of dumbbell domains subjected to joint static bias field and in-plane field","authors":"Wang Yuan-fei, Han Bao-shan","doi":"10.1088/1004-423X/8/7/010","DOIUrl":"https://doi.org/10.1088/1004-423X/8/7/010","url":null,"abstract":"Experiments were statistically carried out on the behavior of vertical-Bloch-line (VBL) chains in the walls of the second kind of dumbbell domains (IIDs) is garnet bubble films subjected to joint action of static bias field H-b and in-plane field H-ip. The curves of the four critical in-plane fields, (H-ip)(IID-ID) (Hip)(IID-OHB) (Hip)(IID-SB) and H-ip' vs H-b were measured and explained. In particular, in terms of two series of IID photos, a new experimental manifestation of the unknown \"number effect\" of VBL chains was found.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"24 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133170197","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 : 1999-07-01DOI: 10.1088/1004-423X/8/7/003
Chen Yang, Pei Lin-Sen, Jin Jin, Ran Qin, Chen Cong-xiang, Yu Shu-qin, Ma Xingxiao
The resonance-enhanced multiphoton ionization (REMPI) spectra of atomic chlorine and bromine in the range of 230-245 nm and 250-285 nm were obtained by using REMPI and time of flight (TOF) techniques. There are twenty-six lines for Cl and twenty-three for Br in the spectra, among which five transitions of Cl and four of Br are observed for the first time. These lines are due to transitions from the Cl(3p 2P3/20, 2P1/20) and Br(4p 2P3/20, 2P1/20) states to upper states induced by two-photon excitation. It is found that the Stark shift of different excited states are almost the same, and they are independent of the S, L, and J quantum numbers of the excited state.
{"title":"RESONANCE-ENHANCED MULTIPHOTON IONIZATION SPECTRA OF THE HALOGEN ATOMS","authors":"Chen Yang, Pei Lin-Sen, Jin Jin, Ran Qin, Chen Cong-xiang, Yu Shu-qin, Ma Xingxiao","doi":"10.1088/1004-423X/8/7/003","DOIUrl":"https://doi.org/10.1088/1004-423X/8/7/003","url":null,"abstract":"The resonance-enhanced multiphoton ionization (REMPI) spectra of atomic chlorine and bromine in the range of 230-245 nm and 250-285 nm were obtained by using REMPI and time of flight (TOF) techniques. There are twenty-six lines for Cl and twenty-three for Br in the spectra, among which five transitions of Cl and four of Br are observed for the first time. These lines are due to transitions from the Cl(3p 2P3/20, 2P1/20) and Br(4p 2P3/20, 2P1/20) states to upper states induced by two-photon excitation. It is found that the Stark shift of different excited states are almost the same, and they are independent of the S, L, and J quantum numbers of the excited state.","PeriodicalId":188146,"journal":{"name":"Acta Physica Sinica (overseas Edition)","volume":"376 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122437126","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}
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