Mesoscopic systems,including nanowires,quantum dots and two-dimensional electron gases,are excellent platforms for studying emerging quantum phenomena,especially in the field of electrical transport.Quantum transport ...Mesoscopic systems,including nanowires,quantum dots and two-dimensional electron gases,are excellent platforms for studying emerging quantum phenomena,especially in the field of electrical transport.Quantum transport covers vast scopes of condensed matter physics,such as superconductivity,quantum Hall effect,and many investigations in mesoscopic devices.展开更多
With the help of scattering-matrix method, the acoustic phonon ballistic transmission and the thermal conductivity are studied detailedly in a four-terminal structure. We find that the transmission coefficients and th...With the help of scattering-matrix method, the acoustic phonon ballistic transmission and the thermal conductivity are studied detailedly in a four-terminal structure. We find that the transmission coefficients and the reduced thermal conductance for each region sensitively depend on geometric parameters, and are of quantum character, but the reduced total thermal conductance for all regions seems independent of structure parameters when the temperature is not very low. Our results show that one can control the thermal conductivity for each region to match practical requirements in devices by adjusting the geometric parameters.展开更多
This paper presents a comprehensive review of the wave-flmction approach for derivation of the number- resolved Master equations, used for description of transport and measurement in mesoseopie systems. The review con...This paper presents a comprehensive review of the wave-flmction approach for derivation of the number- resolved Master equations, used for description of transport and measurement in mesoseopie systems. The review contains important amendments, clarifying subtle points in derivation of the Master equa- tions and their validity. This completes the earlier works on the subject. It is demonstrated that the derivation does not assume weak coupling with the environment and reservoirs, but needs only high bias condition. This condition is very essential for validity of the Markovian Master equations, widely used for a phenomenological description of different physical processes.展开更多
The tunneling of macroscopic object is one of the most fascinating phenomena in condensed matter physics. During the last decade, the problem of quantum tunneling of magnetization in nanometer-scale magnets has attrac...The tunneling of macroscopic object is one of the most fascinating phenomena in condensed matter physics. During the last decade, the problem of quantum tunneling of magnetization in nanometer-scale magnets has attracted a great deal of theoretical and experimental interest. A review of recent theoretical research of the macroscopic quantum phenomena in nanometer-scale single-domain magnets is presented in this paper. It includes macroscopic quantum tunneling (MQT) and coherence (MQC) in single-domain magnetic particles, the topological phase interference or spin-parity effects, and tunneling of magnetization in an arbitrarily directed magnetic field. The general formulas are shown to evaluate the tunneling rate and the tunneling level splitting for single-domain AFM particles. A nontrivial generalization of Kramers degeneracy for double-well system is provided to coherently spin tunneling for spin systems with m-fold rotational symmetry. The effects induced by the external magnetic field have been studied, where the field is along the easy, medium, hard axis, or arbitrary direction.展开更多
文摘Mesoscopic systems,including nanowires,quantum dots and two-dimensional electron gases,are excellent platforms for studying emerging quantum phenomena,especially in the field of electrical transport.Quantum transport covers vast scopes of condensed matter physics,such as superconductivity,quantum Hall effect,and many investigations in mesoscopic devices.
基金The project supported by the Natural Science Foundation of Hubei Province of China under Grant No. 2003ABA004
文摘With the help of scattering-matrix method, the acoustic phonon ballistic transmission and the thermal conductivity are studied detailedly in a four-terminal structure. We find that the transmission coefficients and the reduced thermal conductance for each region sensitively depend on geometric parameters, and are of quantum character, but the reduced total thermal conductance for all regions seems independent of structure parameters when the temperature is not very low. Our results show that one can control the thermal conductivity for each region to match practical requirements in devices by adjusting the geometric parameters.
文摘This paper presents a comprehensive review of the wave-flmction approach for derivation of the number- resolved Master equations, used for description of transport and measurement in mesoseopie systems. The review contains important amendments, clarifying subtle points in derivation of the Master equa- tions and their validity. This completes the earlier works on the subject. It is demonstrated that the derivation does not assume weak coupling with the environment and reservoirs, but needs only high bias condition. This condition is very essential for validity of the Markovian Master equations, widely used for a phenomenological description of different physical processes.
文摘The tunneling of macroscopic object is one of the most fascinating phenomena in condensed matter physics. During the last decade, the problem of quantum tunneling of magnetization in nanometer-scale magnets has attracted a great deal of theoretical and experimental interest. A review of recent theoretical research of the macroscopic quantum phenomena in nanometer-scale single-domain magnets is presented in this paper. It includes macroscopic quantum tunneling (MQT) and coherence (MQC) in single-domain magnetic particles, the topological phase interference or spin-parity effects, and tunneling of magnetization in an arbitrarily directed magnetic field. The general formulas are shown to evaluate the tunneling rate and the tunneling level splitting for single-domain AFM particles. A nontrivial generalization of Kramers degeneracy for double-well system is provided to coherently spin tunneling for spin systems with m-fold rotational symmetry. The effects induced by the external magnetic field have been studied, where the field is along the easy, medium, hard axis, or arbitrary direction.
