Majorana fermions(MFs) are exotic particles that are their own anti-particles. Currently, the search for MFs occurring as quasiparticle excitations in condensed matter systems has attracted widespread interest, becaus...Majorana fermions(MFs) are exotic particles that are their own anti-particles. Currently, the search for MFs occurring as quasiparticle excitations in condensed matter systems has attracted widespread interest, because of their importance in fundamental physics and potential applications in topological quantum computation based on solid-state devices. Motivated by recent experimental progress towards the detection and manipulation of MFs in hybrid semiconductor/superconductor heterostructures, in this review, we present a novel proposal to probe MFs in all-optical domain. We introduce a single quantum dot(QD), a hybrid quantum dot-nanomechanical resonators(QD-NR) system, and a carbon nanotube(CNT) resonator implanted in a single electron spin system with optical pump-probe technology to detect MFs, respectively. With this scheme, a possible Majorana signature is investigated via the probe absorption spectrum and nonlinear optical Kerr effect, and the coupling strength between MFs and the QD or the single electron spin is also determined. In the hybrid QD-NR system, vibration of the NR will enhance the nonlinear optical effect, which makes the MFs more sensitive for detection. In the CNT resonator with a single electron, the single electron spin can be considered as a sensitive probe, and the CNT resonator behaved as a phonon cavity is robust for detecting of MFs. This optical scheme will provide another method for the detection MFs and will open the door for new applications ranging from robust manipulation of MFs to quantum information processing based on MFs.展开更多
Handover location technology was employed for collecting road traffic information in a number of field projects, and the project results demonstrate that it is a supplementary and promising means of road traffic infor...Handover location technology was employed for collecting road traffic information in a number of field projects, and the project results demonstrate that it is a supplementary and promising means of road traffic information collection for further traffic supervision and maintenance. Because handover location technology is one kind of pattern matching based location technologies, offiine handovex location positioning is an essential problem to be studied for successfully matching mobile probes on GIS map. Offline handover location positioning method involves two stages, handover location positioning respectively via two weighted models and an optimized model based on the intermediate results obtained in the first stage. A preliminary field test is conducted on a stretch of freeway in the inner suburban region in Beijing, and performance evaluation results show that the proposed method is superior to standard least square model in location accuracy and location precision, which is an effective method of offline handover location positioning.展开更多
In order to understand the contact phenomena of micron‐sized particles,which have a tremendous impact on a variety of applications in industry and technology,direct access to the loads as well as the displacements ac...In order to understand the contact phenomena of micron‐sized particles,which have a tremendous impact on a variety of applications in industry and technology,direct access to the loads as well as the displacements accompanying such contacts are mandatory.Typical particle ensembles show a size variation ranging from the nanometer to the tenths of micron scale.Especially the contact behavior of particles featuring radii of several up to several tenths of microns is scarcely studied as these particles are typically too large for atomic force microscopy(AFM)based approaches and too small for conventional macroscopic testing setups.In this work a nanoindenter based approach is introduced to gain insight into the contact mechanics of micron‐sized glass beads sliding on rough silicon surfaces at various constant low normal loads.The results are analyzed by a simple modified Coulomb friction law,as well as Hertz,JKR,and DMT contact theory.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.10974133 and 11274230)the Basic Research Program of the Committee of Science and Technology of Shanghai(Grant No.14JC1491700)
文摘Majorana fermions(MFs) are exotic particles that are their own anti-particles. Currently, the search for MFs occurring as quasiparticle excitations in condensed matter systems has attracted widespread interest, because of their importance in fundamental physics and potential applications in topological quantum computation based on solid-state devices. Motivated by recent experimental progress towards the detection and manipulation of MFs in hybrid semiconductor/superconductor heterostructures, in this review, we present a novel proposal to probe MFs in all-optical domain. We introduce a single quantum dot(QD), a hybrid quantum dot-nanomechanical resonators(QD-NR) system, and a carbon nanotube(CNT) resonator implanted in a single electron spin system with optical pump-probe technology to detect MFs, respectively. With this scheme, a possible Majorana signature is investigated via the probe absorption spectrum and nonlinear optical Kerr effect, and the coupling strength between MFs and the QD or the single electron spin is also determined. In the hybrid QD-NR system, vibration of the NR will enhance the nonlinear optical effect, which makes the MFs more sensitive for detection. In the CNT resonator with a single electron, the single electron spin can be considered as a sensitive probe, and the CNT resonator behaved as a phonon cavity is robust for detecting of MFs. This optical scheme will provide another method for the detection MFs and will open the door for new applications ranging from robust manipulation of MFs to quantum information processing based on MFs.
基金Projects(71131001,60874078) supported by the National Natural Science Foundation of ChinaProject(NCET-08-0718) supported by Program for New Century Excellent Talents in University of China
文摘Handover location technology was employed for collecting road traffic information in a number of field projects, and the project results demonstrate that it is a supplementary and promising means of road traffic information collection for further traffic supervision and maintenance. Because handover location technology is one kind of pattern matching based location technologies, offiine handovex location positioning is an essential problem to be studied for successfully matching mobile probes on GIS map. Offline handover location positioning method involves two stages, handover location positioning respectively via two weighted models and an optimized model based on the intermediate results obtained in the first stage. A preliminary field test is conducted on a stretch of freeway in the inner suburban region in Beijing, and performance evaluation results show that the proposed method is superior to standard least square model in location accuracy and location precision, which is an effective method of offline handover location positioning.
基金The authors would like to thank Dr.H.Zhuang,University of Siegen,for his support in preparing rough silicon surfaces and the German Research Foundation(DFG)for financial support under grant Nos.STA 1021/1‐1 and STA 1021/1‐2.The work is carried out within the framework of the Key Research Program(SPP 1486)“Particle in Contact”.
文摘In order to understand the contact phenomena of micron‐sized particles,which have a tremendous impact on a variety of applications in industry and technology,direct access to the loads as well as the displacements accompanying such contacts are mandatory.Typical particle ensembles show a size variation ranging from the nanometer to the tenths of micron scale.Especially the contact behavior of particles featuring radii of several up to several tenths of microns is scarcely studied as these particles are typically too large for atomic force microscopy(AFM)based approaches and too small for conventional macroscopic testing setups.In this work a nanoindenter based approach is introduced to gain insight into the contact mechanics of micron‐sized glass beads sliding on rough silicon surfaces at various constant low normal loads.The results are analyzed by a simple modified Coulomb friction law,as well as Hertz,JKR,and DMT contact theory.
