The vibrational state-selected population transfer from a highly vibrationally excited level to the ground level is of great importance in the preparation of ultra-cold molecules. By using the time-dependent quantum-w...The vibrational state-selected population transfer from a highly vibrationally excited level to the ground level is of great importance in the preparation of ultra-cold molecules. By using the time-dependent quantum-wave-packet method, the population transfer dynamics is investigated theoretically for the HF molecule. A double-E-type laser scheme is proposed to transfer the population from the ｜v=16〉 level to the ground vibrational level ｜v=0〉 on the ground electronic state. The scheme consists of two steps： The first step is to transfer the population from ｜v=16〉 to ｜v=7〉 via an intermediate level ｜v=11〉, and the second one is to transfer the population from ｜v=7〉 to ｜v=0〉 via ｜v=3〉. In each step, three vibrational levels form a E-type population transfer path under the action of two temporally overlapped laser pulses. The maximal population-transfer efficiency is obtained by optimizing the laser inten- sities, frequencies, and relative delays. Cases for the pulses in intuitive and counterintuitive sequences are both calculated and compared. It is found that for both cases the population can be efficiently （over 90%） transferred from the ｜v=-16〉 level to the ｜v=0〉 level.展开更多
We investigate the interference of a kicked harmonic oscillator in phase space.With the measure of interference defined in Lee and Jeong[Phys.Rev.Lett.106(2011)220401],we show that interference increases more rapidly ...We investigate the interference of a kicked harmonic oscillator in phase space.With the measure of interference defined in Lee and Jeong[Phys.Rev.Lett.106(2011)220401],we show that interference increases more rapidly in the chaotic regime than in the regular regime,and that the sub-Planck structure is of importance for the decoherence time in the chaotic regime.We also find that interference plays an important role in energy transport between the kicking fields and the kicked harmonic oscillator.展开更多
Behavioral ＂traditions＂, i.e. behavioral patterns that are acquired with the aid of social learning and that are relatively stable in a group, have been observed in several species. Recently, however, it has been qu...Behavioral ＂traditions＂, i.e. behavioral patterns that are acquired with the aid of social learning and that are relatively stable in a group, have been observed in several species. Recently, however, it has been questioned whether non-human social learning is faithful enough to stabilize those patterns. The observed stability could be interpreted as a result of various constraints that limit the number of possible alternative behaviors, rather than of the fidelity of transmission mechanisms. Those constraints can be roughly described as ＂internal＂, such as mechanical （bodily） properties or cognitive limitations and predispositions, and ＂ex- ternal＂, such as ecological availability or pressures. Here we present an evolutionary individual-based model that explores the re- lationships between the evolution of faithful social learning and behavioral constraints, represented both by the size of the beha- vioral repertoire and by the ＂shape＂ of the search space of a given task. We show that the evolution of high-fidelity transmission mechanisms, when associated with costs （e.g. cognitive, biomechanical, energetic, etc.）, is only likely if the potential behavioral repertoire of a species is large and if the search space does not provide information that can be exploited by individual learning. Moreover we show how stable behavioral patterns （＂traditions＂） can be achieved at the population level as an outcome of both high-fidelity and low-fidelity transmission mechanisms, given that the latter are coupled with a small behavioral repertoire or with a search space that provide substantial feedback. Finally, by introducing the possibility of environmental change, we show that intermediate rates of change favor the evolution of faithful social learning展开更多
The rapid miniaturization of elect, ronic devices motivates research interests in quantum transport.Recently time-dependent quantum transport has become an important research topic. Here we re- view recent progresses ...The rapid miniaturization of elect, ronic devices motivates research interests in quantum transport.Recently time-dependent quantum transport has become an important research topic. Here we re- view recent progresses in the development of time-dependent density-functional theory for quantum transport including the theoretical foundation and numerical algorithms. In particular, the reducedsingle electron density matrix based hierarchical equation of motion, which can be derived from Liouville---von Neumann equation, is reviewed in details. The numerical implementation is discussed and simulation results of realistic devices will be given.展开更多
Quantum state transfer(QST) is an important task in quantum information processing. In this study, we describe two approaches for the high-fidelity transfer of a quantum state between two opposite quantum dots attache...Quantum state transfer(QST) is an important task in quantum information processing. In this study, we describe two approaches for the high-fidelity transfer of a quantum state between two opposite quantum dots attached to a multi-channel quantum network.First, we demonstrate that a high-efficiency QST can be achieved with the coherent time evolution of a quantum system without any external control. Second, we present an approach that uses an alternative mechanism for a high-fidelity QST. By adiabatically varying tunnel couplings, it is possible to implement the complete transmission of a quantum state based on this quantum mechanical mechanism.展开更多
基金Li-hang Li thanks Dr. Yin Huang for assistance. The project is supported by the Specialized Research Fund for the Doctoral Program of Higher Education （No.20130041120053）, SRF for ROCS, SEM, the Sci- ence and Technology Research Funds of the Depart- ment of Education of Liaoning Province （L2013014）, the National Magnetic Confinement Fusion Science Pro- gram （No.2013GB109005）, the Fundamental Research Funds for the Central Universities （DUT12RC（3）60）, and the NationM Natural Science Foundation of China （No.21473018, No.10974024, and No.11274056）.
文摘The vibrational state-selected population transfer from a highly vibrationally excited level to the ground level is of great importance in the preparation of ultra-cold molecules. By using the time-dependent quantum-wave-packet method, the population transfer dynamics is investigated theoretically for the HF molecule. A double-E-type laser scheme is proposed to transfer the population from the ｜v=16〉 level to the ground vibrational level ｜v=0〉 on the ground electronic state. The scheme consists of two steps： The first step is to transfer the population from ｜v=16〉 to ｜v=7〉 via an intermediate level ｜v=11〉, and the second one is to transfer the population from ｜v=7〉 to ｜v=0〉 via ｜v=3〉. In each step, three vibrational levels form a E-type population transfer path under the action of two temporally overlapped laser pulses. The maximal population-transfer efficiency is obtained by optimizing the laser inten- sities, frequencies, and relative delays. Cases for the pulses in intuitive and counterintuitive sequences are both calculated and compared. It is found that for both cases the population can be efficiently （over 90%） transferred from the ｜v=-16〉 level to the ｜v=0〉 level.
基金Supported by Talent Introduction Foundation of Kunming University of Science and Technology under Grant No.kksy201207034
文摘We investigate the interference of a kicked harmonic oscillator in phase space.With the measure of interference defined in Lee and Jeong[Phys.Rev.Lett.106(2011)220401],we show that interference increases more rapidly in the chaotic regime than in the regular regime,and that the sub-Planck structure is of importance for the decoherence time in the chaotic regime.We also find that interference plays an important role in energy transport between the kicking fields and the kicked harmonic oscillator.
文摘Behavioral ＂traditions＂, i.e. behavioral patterns that are acquired with the aid of social learning and that are relatively stable in a group, have been observed in several species. Recently, however, it has been questioned whether non-human social learning is faithful enough to stabilize those patterns. The observed stability could be interpreted as a result of various constraints that limit the number of possible alternative behaviors, rather than of the fidelity of transmission mechanisms. Those constraints can be roughly described as ＂internal＂, such as mechanical （bodily） properties or cognitive limitations and predispositions, and ＂ex- ternal＂, such as ecological availability or pressures. Here we present an evolutionary individual-based model that explores the re- lationships between the evolution of faithful social learning and behavioral constraints, represented both by the size of the beha- vioral repertoire and by the ＂shape＂ of the search space of a given task. We show that the evolution of high-fidelity transmission mechanisms, when associated with costs （e.g. cognitive, biomechanical, energetic, etc.）, is only likely if the potential behavioral repertoire of a species is large and if the search space does not provide information that can be exploited by individual learning. Moreover we show how stable behavioral patterns （＂traditions＂） can be achieved at the population level as an outcome of both high-fidelity and low-fidelity transmission mechanisms, given that the latter are coupled with a small behavioral repertoire or with a search space that provide substantial feedback. Finally, by introducing the possibility of environmental change, we show that intermediate rates of change favor the evolution of faithful social learning
文摘The rapid miniaturization of elect, ronic devices motivates research interests in quantum transport.Recently time-dependent quantum transport has become an important research topic. Here we re- view recent progresses in the development of time-dependent density-functional theory for quantum transport including the theoretical foundation and numerical algorithms. In particular, the reducedsingle electron density matrix based hierarchical equation of motion, which can be derived from Liouville---von Neumann equation, is reviewed in details. The numerical implementation is discussed and simulation results of realistic devices will be given.
基金supported by the National Natural Science Foundation of China(Grant Nos.1142243711174027+2 种基金11105086and 11121403)the National Basic Research Program of China(Grants Nos.2012CB922104and 2014CB921403)
文摘Quantum state transfer(QST) is an important task in quantum information processing. In this study, we describe two approaches for the high-fidelity transfer of a quantum state between two opposite quantum dots attached to a multi-channel quantum network.First, we demonstrate that a high-efficiency QST can be achieved with the coherent time evolution of a quantum system without any external control. Second, we present an approach that uses an alternative mechanism for a high-fidelity QST. By adiabatically varying tunnel couplings, it is possible to implement the complete transmission of a quantum state based on this quantum mechanical mechanism.
