The spin-polarized linear conductance spectrum and current–voltage characteristics in a four-quantum-dot ring embodied into Aharonov–Bohm （AB） interferometer are investigated theoretically by considering a local R...The spin-polarized linear conductance spectrum and current–voltage characteristics in a four-quantum-dot ring embodied into Aharonov–Bohm （AB） interferometer are investigated theoretically by considering a local Rashba spin–orbit interaction. It shows that the spin-polarized linear conductance and the corresponding spin polarization are each a function of magnetic flux phase at zero bias voltage with a period of 2π, and that Hubbard U cannot influence the electron transport properties in this case. When adjusting appropriately the structural parameter of inter-dot coupling and dot-lead coupling strength, the electronic spin polarization can reach a maximum value. Furthermore, by adjusting the bias voltages applied to the leads, the spin-up and spin-down currents move in opposite directions and pure spin current exists in the configuration space in appropriate situations. Based on the numerical results, such a model can be applied to the design of a spin filter device.展开更多
The Aharonov-Bohm effect (experimentally verified) constitutes an undubitable proof of the non local nature of quantum mechanics and of the gauge character of the electromagnetic interaction. On the other hand, the ex...The Aharonov-Bohm effect (experimentally verified) constitutes an undubitable proof of the non local nature of quantum mechanics and of the gauge character of the electromagnetic interaction. On the other hand, the existence of a Dirac monopole (not yet experimentally confirmed) leads to the quantization of the electric charge. Both phenomena can be mathematically described in the context of fiber bundle theory. Using this approach, we briefly review the mutual determination of the corresponding connections ωA−B, ωDand potentials AA−B±, AD±. This mathematical result gives an additional theoretical support to present day active search of the magnetic charge.展开更多
We study the dynamic of scalar bosons in the presence of Aharonov-Bohm magnetic field. First, we give the differential equation that governs this dynamic. Secondly, we use variational techniques to show that the follo...We study the dynamic of scalar bosons in the presence of Aharonov-Bohm magnetic field. First, we give the differential equation that governs this dynamic. Secondly, we use variational techniques to show that the following Schrödinger-Newton equation: , where A is an Aharonov-Bohm magnetic potential, has a unique ground-state solution.展开更多
By using the non-equilibrium Green＇s function technique, we investigate the electronic transport properties in an Aharonov-Bohm interferometer coupling with Majorana fermions. We find a fixed unit conductance peak wh...By using the non-equilibrium Green＇s function technique, we investigate the electronic transport properties in an Aharonov-Bohm interferometer coupling with Majorana fermions. We find a fixed unit conductance peak which is in-dependent of the other factors when the topological superconductor is grounded. Especially, an additional phase appears when the topological superconductor is in the strong Coulomb regime, which induces a new conductance resonant peak compared with the structure of replacing the topological superconductor by a quantum dot, and the conductance oscillation with the magnetic flux reveals a 2π phase shift by raising （lowering） a charge on the capacitor.展开更多
This paper investigates the electronic transport properties in an Aharonov Bohm interferometer with a quantum dot coupling to left and right electrodes. By employing cluster expansions, it transforms the equations of ...This paper investigates the electronic transport properties in an Aharonov Bohm interferometer with a quantum dot coupling to left and right electrodes. By employing cluster expansions, it transforms the equations of motion of Green＇s functions into the corresponding equation of motion of connected Green＇s functions, which provides a natural and uniform truncation scheme. With this method under the Lacroix＇s truncation approximation, it shows that the asymmetric line shape of zero bias conductance manifests itself as the Fano effect, and the Kondo effect has been observed in the narrow peak of differential conductance curve of the system. Our numerical results also show that the building of Fano state suppresses the amplitude of Kondo resonance.展开更多
With the help of nonequilibrium Green＇s function technique, the electronic transport through series Aharonov-Bohm （AB） interferometers is investigated. We obtain the AB interference pattern of the transition probab...With the help of nonequilibrium Green＇s function technique, the electronic transport through series Aharonov-Bohm （AB） interferometers is investigated. We obtain the AB interference pattern of the transition probability characterized by the Mgebraic sum φ and the difference θ of two magnetic fluxes, and particularly a general rule of AB oscillation period depending on the ratio of integer quantum numbers of the fluxes. A parity effect is observed, showing the asymmetric AB oscillations with respect to the even and odd quantum numbers of the total flux in antiparallel AB interferometers. It is also shown that the AB flux can shift the Fano resonance peaks of the transmission spectrum.展开更多
This paper theoretically reports the nonlocal Andreev reflection and spin current in a normal metal-ferromagnetic metal-superconducting Aharonov-Bohm interferometer. It is found that the electronic current and spin cu...This paper theoretically reports the nonlocal Andreev reflection and spin current in a normal metal-ferromagnetic metal-superconducting Aharonov-Bohm interferometer. It is found that the electronic current and spin current are sensitive to systematic parameters, such as the gate voltage of quantum dots and the external magnetic flux. The electronic current in the normal metal lead results from two competing processes： quasiparticle transmission and nonlocal Andreev reflection. The appearance of zero spin-up electronic current （or spin-down electronic current） signals the existence of nonlocal Andreev reflection, and the presence of zero electronic current results in the appearance of pure spin current.展开更多
We investigate the time-modulated electronic and spin transport properties through two T-shaped three-quantum-dot molecules embedded in an Aharonov-Bohm（A-B） interferometer. By using the Keldysh non-equilibrium Gree...We investigate the time-modulated electronic and spin transport properties through two T-shaped three-quantum-dot molecules embedded in an Aharonov-Bohm（A-B） interferometer. By using the Keldysh non-equilibrium Green＇s function technique, the photon-assisted spin-dependent average current is analyzed. The T-shaped three-quantum-dot molecule A-B interferometer exhibits excellent controllability in the average current resonance spectra by adjusting the interdot coupling strength, Rashba spin-orbit coupling strength, magnetic flux, and amplitude of the time-dependent external field.Efficient spin filtering and multiple electron-photon pump functions are exploited in the multi-quantum-dot molecule A-B interferometer by a time-modulated external field.展开更多
By applying the slave boson technique, we have studied the electron transport through double-dotAharonov-Bohm interferometer in the Kondo regime. For the system with symmetric quantum dots, the linear con-ductance is ...By applying the slave boson technique, we have studied the electron transport through double-dotAharonov-Bohm interferometer in the Kondo regime. For the system with symmetric quantum dots, the linear con-ductance is shown to be enhanced by Kondo effect, but it is suppressed in the deep dot level regime in the presence ofnonzero magnetic flux. The Aharonov Bohm oscillations of the conductance are also investigated.展开更多
基金Project supported by the Natural Science Foundation of Liaoning Province, China (Grant No. 201202085)the National Natural Science Foundation of China(Grant No. 11004138)+1 种基金the Excellent Young Scientists Fund of Liaoning Provence, China (Grant No. LJQ2011020)the Young Scientists Fund of Shenyang Ligong University (Grant No. 2011QN-04-11)
文摘The spin-polarized linear conductance spectrum and current–voltage characteristics in a four-quantum-dot ring embodied into Aharonov–Bohm （AB） interferometer are investigated theoretically by considering a local Rashba spin–orbit interaction. It shows that the spin-polarized linear conductance and the corresponding spin polarization are each a function of magnetic flux phase at zero bias voltage with a period of 2π, and that Hubbard U cannot influence the electron transport properties in this case. When adjusting appropriately the structural parameter of inter-dot coupling and dot-lead coupling strength, the electronic spin polarization can reach a maximum value. Furthermore, by adjusting the bias voltages applied to the leads, the spin-up and spin-down currents move in opposite directions and pure spin current exists in the configuration space in appropriate situations. Based on the numerical results, such a model can be applied to the design of a spin filter device.
文摘The Aharonov-Bohm effect (experimentally verified) constitutes an undubitable proof of the non local nature of quantum mechanics and of the gauge character of the electromagnetic interaction. On the other hand, the existence of a Dirac monopole (not yet experimentally confirmed) leads to the quantization of the electric charge. Both phenomena can be mathematically described in the context of fiber bundle theory. Using this approach, we briefly review the mutual determination of the corresponding connections ωA−B, ωDand potentials AA−B±, AD±. This mathematical result gives an additional theoretical support to present day active search of the magnetic charge.
文摘We study the dynamic of scalar bosons in the presence of Aharonov-Bohm magnetic field. First, we give the differential equation that governs this dynamic. Secondly, we use variational techniques to show that the following Schrödinger-Newton equation: , where A is an Aharonov-Bohm magnetic potential, has a unique ground-state solution.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB922103)
文摘By using the non-equilibrium Green＇s function technique, we investigate the electronic transport properties in an Aharonov-Bohm interferometer coupling with Majorana fermions. We find a fixed unit conductance peak which is in-dependent of the other factors when the topological superconductor is grounded. Especially, an additional phase appears when the topological superconductor is in the strong Coulomb regime, which induces a new conductance resonant peak compared with the structure of replacing the topological superconductor by a quantum dot, and the conductance oscillation with the magnetic flux reveals a 2π phase shift by raising （lowering） a charge on the capacitor.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10375039 and 90503008）, the Doctoral Fund of Ministry of Education of China, and partly by the Center of Theoretical Nuclear Physics of Heavy Ion Research Facilities of Lanzhou of China.
文摘This paper investigates the electronic transport properties in an Aharonov Bohm interferometer with a quantum dot coupling to left and right electrodes. By employing cluster expansions, it transforms the equations of motion of Green＇s functions into the corresponding equation of motion of connected Green＇s functions, which provides a natural and uniform truncation scheme. With this method under the Lacroix＇s truncation approximation, it shows that the asymmetric line shape of zero bias conductance manifests itself as the Fano effect, and the Kondo effect has been observed in the narrow peak of differential conductance curve of the system. Our numerical results also show that the building of Fano state suppresses the amplitude of Kondo resonance.
基金Project supported by the National Natural Science Foundation of China （Grant No 10475053）.
文摘With the help of nonequilibrium Green＇s function technique, the electronic transport through series Aharonov-Bohm （AB） interferometers is investigated. We obtain the AB interference pattern of the transition probability characterized by the Mgebraic sum φ and the difference θ of two magnetic fluxes, and particularly a general rule of AB oscillation period depending on the ratio of integer quantum numbers of the fluxes. A parity effect is observed, showing the asymmetric AB oscillations with respect to the even and odd quantum numbers of the total flux in antiparallel AB interferometers. It is also shown that the AB flux can shift the Fano resonance peaks of the transmission spectrum.
基金Project supported by the Special Funds of the National Natural Science Foundation of China (Grant Nos 10847133 and 10847132)the Natural Science Foundation of Education Bureau of Jiangsu Province,China (Grant No 08KJB140002)
文摘This paper theoretically reports the nonlocal Andreev reflection and spin current in a normal metal-ferromagnetic metal-superconducting Aharonov-Bohm interferometer. It is found that the electronic current and spin current are sensitive to systematic parameters, such as the gate voltage of quantum dots and the external magnetic flux. The electronic current in the normal metal lead results from two competing processes： quasiparticle transmission and nonlocal Andreev reflection. The appearance of zero spin-up electronic current （or spin-down electronic current） signals the existence of nonlocal Andreev reflection, and the presence of zero electronic current results in the appearance of pure spin current.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11447132 and 11504042)the Natural Science Foundation of Heilongjiang,China(Grant No.A201405)+2 种基金111 Project to Harbin Engineering University,China(Grant No.B13015)Chongqing Science and Technology Commission Project,China(Grant Nos.cstc2014jcyj A00032 and cstc2016jcyj A1158)Scientific Research Project for Advanced Talents of Yangtze Normal University,China(Grant No.2017KYQD09)
文摘We investigate the time-modulated electronic and spin transport properties through two T-shaped three-quantum-dot molecules embedded in an Aharonov-Bohm（A-B） interferometer. By using the Keldysh non-equilibrium Green＇s function technique, the photon-assisted spin-dependent average current is analyzed. The T-shaped three-quantum-dot molecule A-B interferometer exhibits excellent controllability in the average current resonance spectra by adjusting the interdot coupling strength, Rashba spin-orbit coupling strength, magnetic flux, and amplitude of the time-dependent external field.Efficient spin filtering and multiple electron-photon pump functions are exploited in the multi-quantum-dot molecule A-B interferometer by a time-modulated external field.
基金The project supported by National Natural Science Foundation of China under Grant No.19975031
文摘By applying the slave boson technique, we have studied the electron transport through double-dotAharonov-Bohm interferometer in the Kondo regime. For the system with symmetric quantum dots, the linear con-ductance is shown to be enhanced by Kondo effect, but it is suppressed in the deep dot level regime in the presence ofnonzero magnetic flux. The Aharonov Bohm oscillations of the conductance are also investigated.
