The mesoscopic quantum interference phenomenon （QIP） can be observed and behaves as the oscillation of conductance in nano-devices when the external magnetic field changes. Excluding the factor of impurities or defe...The mesoscopic quantum interference phenomenon （QIP） can be observed and behaves as the oscillation of conductance in nano-devices when the external magnetic field changes. Excluding the factor of impurities or defects, specific QIP is determined by the sample geometry. We have improved a first-principles method based on the matrix Green＇s function and the density functional theory to simulate the transport behaviour of such systems under a magnetic field. We have studied two kinds of QIP： universal conductance fluctuation （UCF） and Aharonov Bohm effect （A-B effect）. We find that the amplitude of UCF is much smaller than the previous theoretical prediction. We have discussed the origin of difference and concluded that due to the failure of ergodic hypothesis, the ensemble statistics is not applicable, and the conductance fluctuation is determined by the flux-dependent density of states （DOSs）. We have also studied the relation between the UCF and the structure of sample. For a specific structure, an atomic circle, the A-B effect is observed and the origin of the oscillation is also discussed.展开更多
Single-ion magnets(SIMs)are prominent candidates for promoting new technologies in quantum information processing(QIP).Herein,we present two new isostructural oxamato derivatives,namely,{n-Bu_(4)N[Ln(H_(2)edpba)_(2)]}...Single-ion magnets(SIMs)are prominent candidates for promoting new technologies in quantum information processing(QIP).Herein,we present two new isostructural oxamato derivatives,namely,{n-Bu_(4)N[Ln(H_(2)edpba)_(2)]}_(n),Ln=Tb^(3+)(1)and Gd^(3+)(2)[H_(2)edpba^(2-)=N,N’-2,2’-ethylenediphenylenebis(oxamate)],that are thermostable up to∼290℃.Single-crystal X-ray diffraction reveals that 1 and 2 are one-dimensional coordination polymers with a ribbon-like structure,and their metal centers are eight-coordinated with a D_(4d) symmetry.Cryomagnetic studies disclose the presence of slow magnetic relaxation(SMR)behavior for 1 and 2.For 1,the Raman effect dominates the SMR at a zero magnetic field,while Raman,Orbach,and reciprocating thermal behavior(RTB)mechanisms arise at higher fields.Conversely,RTB and the bottleneck effect were observed at 2.Solid-state photoluminescent data display a remarkable green luminescence emission,with intense and sharp bands ranging from 480 to 700 nm in the spectra,which are attributed to the ^(5)D_(4)→^(7)F_(J)(J=6-0)transitions of terbium(Ⅲ)ions.By monitoring the temperaturedependent lifetime of the ^(5)D_(4) state after the intensity decay of the emission band attributed to the ^(5)D_(4)→^(7)F_(5)(546 nm)transition,the complex shows a reasonable thermometric performance with a relative sensitivity of 2.77%K^(-1) at 448 K.1 behaves as a zero-field SIM and as a photoluminescent thermometer.展开更多
Path computation elements （PCEs） are employed to compute end-to-end paths across multi-domain optical networks due to the advantages of powerful computation capability. However, PCEs＇ location selection is still an...Path computation elements （PCEs） are employed to compute end-to-end paths across multi-domain optical networks due to the advantages of powerful computation capability. However, PCEs＇ location selection is still an open problem which is closely related to the communication overhead. This paper mainly focuses on the problem of PCEs＇ location selection to minimize the overall communication overhead in the control plane. The problem is formulated as a quadratic integer programming （QIP） model, and an optimal decision rule is gained from the solution of the QIP model. Then based on the decision rule, a distributed heuristic algorithm is proposed for dynamic network scenario. Simulation results demonstrate the benefit and the effectiveness of our proposed approach by comparing it with random selection policy.展开更多
基金Supported by the National Basic Research Programof China(973 Program)(No.2001CB309300),the NNSF of China (No.10425524 and No.10574125),and the European Commission under Contact(No.007065)(Marie Curie Action).
基金Project supported by the National Natural Science Foundation of China (Grant Nos 90207009, 90206048 and 90406014)
文摘The mesoscopic quantum interference phenomenon （QIP） can be observed and behaves as the oscillation of conductance in nano-devices when the external magnetic field changes. Excluding the factor of impurities or defects, specific QIP is determined by the sample geometry. We have improved a first-principles method based on the matrix Green＇s function and the density functional theory to simulate the transport behaviour of such systems under a magnetic field. We have studied two kinds of QIP： universal conductance fluctuation （UCF） and Aharonov Bohm effect （A-B effect）. We find that the amplitude of UCF is much smaller than the previous theoretical prediction. We have discussed the origin of difference and concluded that due to the failure of ergodic hypothesis, the ensemble statistics is not applicable, and the conductance fluctuation is determined by the flux-dependent density of states （DOSs）. We have also studied the relation between the UCF and the structure of sample. For a specific structure, an atomic circle, the A-B effect is observed and the origin of the oscillation is also discussed.
基金supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)Fundacao de Amparoà Pesquisa do Estado de Minas Gerais(FAPEMIG)+3 种基金Fundacao Carlos Chagas Filho de Amparoà Pesquisa do Estado do Rio de Janeiro(FAPERJ)Fundacao de Aperfeiçoamento de Pessoal de Nível Superior(CAPES,Finance Code 001)the Fundacao de AmparoàPesquisa do Estado de Sao Paulo(FAPESP)for the postdoctoral fellowship(2024/00198-0)for RVP,project 2021/08111-2for funding the EMU Project 2023/17024-1.
文摘Single-ion magnets(SIMs)are prominent candidates for promoting new technologies in quantum information processing(QIP).Herein,we present two new isostructural oxamato derivatives,namely,{n-Bu_(4)N[Ln(H_(2)edpba)_(2)]}_(n),Ln=Tb^(3+)(1)and Gd^(3+)(2)[H_(2)edpba^(2-)=N,N’-2,2’-ethylenediphenylenebis(oxamate)],that are thermostable up to∼290℃.Single-crystal X-ray diffraction reveals that 1 and 2 are one-dimensional coordination polymers with a ribbon-like structure,and their metal centers are eight-coordinated with a D_(4d) symmetry.Cryomagnetic studies disclose the presence of slow magnetic relaxation(SMR)behavior for 1 and 2.For 1,the Raman effect dominates the SMR at a zero magnetic field,while Raman,Orbach,and reciprocating thermal behavior(RTB)mechanisms arise at higher fields.Conversely,RTB and the bottleneck effect were observed at 2.Solid-state photoluminescent data display a remarkable green luminescence emission,with intense and sharp bands ranging from 480 to 700 nm in the spectra,which are attributed to the ^(5)D_(4)→^(7)F_(J)(J=6-0)transitions of terbium(Ⅲ)ions.By monitoring the temperaturedependent lifetime of the ^(5)D_(4) state after the intensity decay of the emission band attributed to the ^(5)D_(4)→^(7)F_(5)(546 nm)transition,the complex shows a reasonable thermometric performance with a relative sensitivity of 2.77%K^(-1) at 448 K.1 behaves as a zero-field SIM and as a photoluminescent thermometer.
基金supported by the National Basic Research Program of China (2010CB328202, 2010CB328204, and 2012CB315604)the Hi-Tech Research and Development Program of China (2012AA011302)+3 种基金the Beijing Nova Program (2011065)the RFDP Project (20120005120019)the Fundamental Research Funds for the Central Universities (2013RC1201)the Fund of State Key Laboratory of Information Photonics and Optical Communications (BUPT)
文摘Path computation elements （PCEs） are employed to compute end-to-end paths across multi-domain optical networks due to the advantages of powerful computation capability. However, PCEs＇ location selection is still an open problem which is closely related to the communication overhead. This paper mainly focuses on the problem of PCEs＇ location selection to minimize the overall communication overhead in the control plane. The problem is formulated as a quadratic integer programming （QIP） model, and an optimal decision rule is gained from the solution of the QIP model. Then based on the decision rule, a distributed heuristic algorithm is proposed for dynamic network scenario. Simulation results demonstrate the benefit and the effectiveness of our proposed approach by comparing it with random selection policy.
