An alternative scheme is presented to generate arbitrary anticorrelated states of a two-mode field. In the scheme, a sequence of A-type three-level atoms are orderly sent across the cavity to interact with the cavity ...An alternative scheme is presented to generate arbitrary anticorrelated states of a two-mode field. In the scheme, a sequence of A-type three-level atoms are orderly sent across the cavity to interact with the cavity field initially in the two-mode vacuum state. The detection of all the atoms in the ground state collapses the two-mode field to the desired state. In this way, we can prepare the anticorrelated states of a two-mode field.展开更多
Diurnal temperature range （DTR） is an im- portant measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of co...Diurnal temperature range （DTR） is an im- portant measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of correlation between the DTR and atmospheric precipitable water （PW） over China is explored using newly homogenized surface weather and sounding observations. The results show that PW changes broadly reflect the geographic patterns of DTR long-term trends over most of China during the period 1970-2012, with significant anticorrelations of trend patterns between the DTR and PW, especially over those regions with higher magnitude DTR trends. PW can largely explain about 40% or more （re 0.40） of the DTR changes, with a d（PW）/d（DTR） slope of -2% to -10% K^-1 over most of northwestern and southeastern China, despite certain seasonal dependencies. For China as whole, the significant anticorrelations between the DTR and PW anomalies range from -0.42 to -0.75, with a d（PW）/d（DTR） slope of-6% to -11% K^-1. This implies that long-term DTR changes are likely to be associated with opposite PW changes, approximately following the Clausius-Clapeyron equation. Furthermore, the relationship is more significant in the warm season than in the cold season. Thus, it is possible that PW can be considered as one potential factor when exploring long-term DTR changes over China. It should be noted that the present study has a largely statistical focus and that the underlying physical processes should therefore be examined in future work.展开更多
Electrons are believed to avoid one another in space(correlation) due to the Coulomb repulsion and/or the Pauli exclusion principle.It is shown, using examples of two-electron systems, that indeed the mean electron-el...Electrons are believed to avoid one another in space(correlation) due to the Coulomb repulsion and/or the Pauli exclusion principle.It is shown, using examples of two-electron systems, that indeed the mean electron-electron distance increases in case of the ground electronic state as compared to the independent electron model. It is demonstrated however that there exist excited states, often of low energy, in which the electrons, while having a lot of free physical space(with nuclei being absent), choose to be close to each other in their motion("anticorrelation"), as if they mutually attracted one another. The source of this effect, quantummechanical in nature, is the orthogonality of the eigenfunctions, that forces the electronic wave functions to differ widely, even at the price of short electron-electron distances. There are also excited states with a mixed behaviour, with complex and often intriguing correlation-anticorrelation patterns.展开更多
基金supported by National Natural Science Foundation of China under Grant No.10674025the Fund of Education Department of Fujian Province under Grant No.JB06043
文摘An alternative scheme is presented to generate arbitrary anticorrelated states of a two-mode field. In the scheme, a sequence of A-type three-level atoms are orderly sent across the cavity to interact with the cavity field initially in the two-mode vacuum state. The detection of all the atoms in the ground state collapses the two-mode field to the desired state. In this way, we can prepare the anticorrelated states of a two-mode field.
基金funded by the National Basic Research Program of China (Grant No. 2012CB956203)the Strategic Priority Research Program-Climate Change: Carbon Budget and Relevant Issues of the Chinese Academy of Sciences (Grant No. XDA05090101)the Climate Change Special Fund of the China Meteorological Administration: Atmospheric Water Vapor Changes in China and Its Causes (Grant No. CCSF201330)
文摘Diurnal temperature range （DTR） is an im- portant measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of correlation between the DTR and atmospheric precipitable water （PW） over China is explored using newly homogenized surface weather and sounding observations. The results show that PW changes broadly reflect the geographic patterns of DTR long-term trends over most of China during the period 1970-2012, with significant anticorrelations of trend patterns between the DTR and PW, especially over those regions with higher magnitude DTR trends. PW can largely explain about 40% or more （re 0.40） of the DTR changes, with a d（PW）/d（DTR） slope of -2% to -10% K^-1 over most of northwestern and southeastern China, despite certain seasonal dependencies. For China as whole, the significant anticorrelations between the DTR and PW anomalies range from -0.42 to -0.75, with a d（PW）/d（DTR） slope of-6% to -11% K^-1. This implies that long-term DTR changes are likely to be associated with opposite PW changes, approximately following the Clausius-Clapeyron equation. Furthermore, the relationship is more significant in the warm season than in the cold season. Thus, it is possible that PW can be considered as one potential factor when exploring long-term DTR changes over China. It should be noted that the present study has a largely statistical focus and that the underlying physical processes should therefore be examined in future work.
文摘Electrons are believed to avoid one another in space(correlation) due to the Coulomb repulsion and/or the Pauli exclusion principle.It is shown, using examples of two-electron systems, that indeed the mean electron-electron distance increases in case of the ground electronic state as compared to the independent electron model. It is demonstrated however that there exist excited states, often of low energy, in which the electrons, while having a lot of free physical space(with nuclei being absent), choose to be close to each other in their motion("anticorrelation"), as if they mutually attracted one another. The source of this effect, quantummechanical in nature, is the orthogonality of the eigenfunctions, that forces the electronic wave functions to differ widely, even at the price of short electron-electron distances. There are also excited states with a mixed behaviour, with complex and often intriguing correlation-anticorrelation patterns.
