Publications (38) View all
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Article: Finite frequency current fluctuations and the self-consistent perturbation theory for electron transport through quantum dot
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ABSTRACT: We have formulated the problem of electron transport through interacting quantum dot system in the framework of self-consistent perturbation theory, and show that the current conservation condition is guaranteed due to the gauge invariant properties of the Green's functions and the generalized Ward identity. By using a generating functional for the statistics of the nonequilibrium system, we have obtained general formulae for calculating the current and the current fluctuations in the presence of arbitrary time-dependent potentials. As demonstration of application, we have studied the interaction effects on the finite frequency noise for electron resonant tunneling through an Anderson impurity, and obtained an analytical equation for the interaction effect on the finite frequency current noise within the Hartree approximation, which is an extension of the previous results obtained by Hershfield on zero frequency shot noise.11/2012; -
Article: Spin-polarized electron transport through graphene nanoribbon with zigzag edges.
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ABSTRACT: We investigate the electron transport through a graphene nanoribbon (GNR) junction with zigzag edges. It is shown that the edge state and the magnetization properties of a GNR greatly influence its electron transport properties. By applying sufficient back-gate voltages to the lead parts of a zigzag GNR, the magnetization of the edges is quenched in the leadings parts, but is preserved in the center part of the junction. Without applying external transverse electric field, we show that, by preparing the junction in a ferromagnetic state, a strongly spin-polarized electron current can be obtained even though the incident electron current has no spin polarization.Journal of Physics Condensed Matter 05/2011; 23(20):205304. · 2.55 Impact Factor -
Article: Spin interference and the Fano effect in electron transport through a mesoscopic ring side-coupled with a quantum dot.
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ABSTRACT: We investigate the electron transport through a mesoscopic ring side-coupled with a quantum dot (QD) in the presence of Rashba spin-orbit (SO) interaction. It is shown that both the Fano resonance and the spin interference effects play important roles in the electron transport properties. As the QD level is around the Fermi energy, the total conductance shows a typical Fano resonance line shape. By applying an electrical gate voltage to the QD, the total transmission through the system can be strongly modulated. By threading the mesoscopic ring with a magnetic flux, the time-reversal symmetry of the system is broken, and a spin polarized current can be obtained even though the incident current is unpolarized.Journal of Physics Condensed Matter 04/2010; 22(13):135301. · 2.55 Impact Factor -
Article: Quantum phase transition and underscreened Kondo effect in electron transport through parallel double quantum dots.
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ABSTRACT: We investigate electronic transport through a parallel double quantum dot (DQD) system with strong on-site Coulomb interaction and capacitive interdot coupling. By applying the numerical renormalization group (NRG) method, the ground state of the system and the transmission probability at zero temperature have been obtained. For a system of quantum dots with degenerate energy levels and small interdot tunnel coupling, the spin correlations between the DQDs is ferromagnetic and the ground state of the system is a spin-1 triplet state. The linear conductance will reach the unitary limit (2e(2)/h) due to the underscreened Kondo effect at low temperature. As the interdot tunnel coupling increases, there is a quantum phase transition from ferromagnetic to antiferromagnetic spin correlation in DQDs and the linear conductance is strongly suppressed.Journal of Physics Condensed Matter 11/2009; 21(45):455303. · 2.55 Impact Factor -
Article: Gene expression profiling-based in silico approach to identify potential vaccine candidates and drug targets against B. pertussis and B. parapertussis.
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ABSTRACT: Whooping cough (pertussis) caused by B. pertussis (B.p) is still serious public health threat. B. parapertussis (B.pp), closely related to B.p, also causes whooping cough. The incidence of B.pp infections has been increasing over the last decades, partly because pertussis vaccines have low efficiency against B.pp infections. Moreover, because the majority of pertussis patients are infants, common antimicrobial agents producing serious adverse reactions in infants are not fully satisfactory. Therefore, we try to identify potential vaccine candidates and alternative drug targets against both B.p and B.pp. This preliminary work integrates several different kinds of data from in silico analysis, comparative genomic hybridization, global transcriptional profiling, and protein-protein interaction (PPI) network to screen potential vaccine candidates and drug targets against the two species. Finally, 191 potential crossprotective vaccine candidates are identified. They have high transcriptional levels in both species, or are associated with virulence and pathogenesis. Moreover, these proteins are not only potentially surface-exposed in the bacteria, but also well conserved among the 165 B.p and B.pp strains. Among them, 22 candidates with high essentiality in the two PPI networks of B.p and B.pp are regarded as suitable drug targets against the two species. We just selected Bordetella as an example to develop a rapid and reliable approach for screening alternative drug targets that associated with novel protein pathways, complexes, and cellular functions against these antibiotic-resistant pathogens. Further researches focusing on the 191 vaccine candidates could accelerate the development of more effective vaccines and drug therapy against B.p and B.pp infection.Omics: a journal of integrative biology 10/2008; 12(3):161-9. · 2.29 Impact Factor
