We study theoretically the nonadiabatic geometric phase of a doubly driven two-level system with an additional relative phase between the two driving modes introduced in. It is shown that the time evolution of the sys...We study theoretically the nonadiabatic geometric phase of a doubly driven two-level system with an additional relative phase between the two driving modes introduced in. It is shown that the time evolution of the system strongly depends on this relative phase. The condition for the system returning to its initial state after a single period is given by the means of the Landau–Zener–Stückelberg–Majorana destructive interference. The nonadiabatic geometric phase accompanying a cyclic evolution is shown to be related to the Stokes phase as well as this relative phase. By controlling the relative phase, the geometric phase can characterize two distinct phases in the adiabatic limit.展开更多
With the socio-economic change that has taken place over the last years,in addition to an increase in sustainability regulation,stakeholders have gained importance and organizations are more active in relation to gene...With the socio-economic change that has taken place over the last years,in addition to an increase in sustainability regulation,stakeholders have gained importance and organizations are more active in relation to generating social impact,but society demands more and better social impact from organizations.The objectives of this paper are to clarify the concepts of impact and social impact optimization,and to detect levers and barriers to help organizations optimize the social impact that they generate.A qualitative approach based on interviews with social impact leaders from organizations with different forms(big companies,small and medium-sized enterprises,corporate foundations,b-corps,community foundations,public and private foundations,associations and investing firms)is applied,together with focus groups with stakeholders from those organizations that are best practices.展开更多
We study the chiral bound states in a coupled-resonator array with staggered hopping strengths,which interacts with a two-level small atom through a single coupling point or two adjacent ones.In addition to the two ty...We study the chiral bound states in a coupled-resonator array with staggered hopping strengths,which interacts with a two-level small atom through a single coupling point or two adjacent ones.In addition to the two typical bound states found above and below the energy bands,this system presents an extraordinary chiral bound state located within the energy gap.We use the chirality to quantify the breaking of the mirror symmetry.We find that the chirality value undergoes continuous changes by tuning the coupling strengths.The preferred direction of the chirality is controlled not only by the competition between the intracell and the intercell hoppings in the coupled-resonator array,but also by the coherence between the two coupling points.In the case with one coupling point,the chirality values varies monotonously with difference between the intracell hopping and the intercell hoppings.While in the case with two coupling points,due to the coherence between the two coupling points the perfect chiral states can be obtained.展开更多
基金the Special Foundation for theoretical physics Research Program of China (Grant No. 11647165)the China Postdoctoral Science Foundation Funded Project (Project No. 2020M673118)+3 种基金the funding from the National Natural Science Foundation of China (Grant No. 11874247)the National Key Research and Development Program of China (Grant No. 2017YFA0304500)the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices, China (Grant No. KF201703)the support from Guangdong Provincial Key Laboratory (Grant No. 2019B121203002)。
文摘We study theoretically the nonadiabatic geometric phase of a doubly driven two-level system with an additional relative phase between the two driving modes introduced in. It is shown that the time evolution of the system strongly depends on this relative phase. The condition for the system returning to its initial state after a single period is given by the means of the Landau–Zener–Stückelberg–Majorana destructive interference. The nonadiabatic geometric phase accompanying a cyclic evolution is shown to be related to the Stokes phase as well as this relative phase. By controlling the relative phase, the geometric phase can characterize two distinct phases in the adiabatic limit.
文摘With the socio-economic change that has taken place over the last years,in addition to an increase in sustainability regulation,stakeholders have gained importance and organizations are more active in relation to generating social impact,but society demands more and better social impact from organizations.The objectives of this paper are to clarify the concepts of impact and social impact optimization,and to detect levers and barriers to help organizations optimize the social impact that they generate.A qualitative approach based on interviews with social impact leaders from organizations with different forms(big companies,small and medium-sized enterprises,corporate foundations,b-corps,community foundations,public and private foundations,associations and investing firms)is applied,together with focus groups with stakeholders from those organizations that are best practices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11975095,12075082,11935006,and 12247105)the Major Sci-Tech Program of Hunan Province,China(Grant No.2023ZJ1010)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2019A1515011400 and 2023A151501223).
文摘We study the chiral bound states in a coupled-resonator array with staggered hopping strengths,which interacts with a two-level small atom through a single coupling point or two adjacent ones.In addition to the two typical bound states found above and below the energy bands,this system presents an extraordinary chiral bound state located within the energy gap.We use the chirality to quantify the breaking of the mirror symmetry.We find that the chirality value undergoes continuous changes by tuning the coupling strengths.The preferred direction of the chirality is controlled not only by the competition between the intracell and the intercell hoppings in the coupled-resonator array,but also by the coherence between the two coupling points.In the case with one coupling point,the chirality values varies monotonously with difference between the intracell hopping and the intercell hoppings.While in the case with two coupling points,due to the coherence between the two coupling points the perfect chiral states can be obtained.
