arXiv subjects

Yu. V. Nazarov

Publications and source records attributed to Yu. V. Nazarov.

79 records · Page 5Linked to original sources

arXiv1997

A coherent double-quantum-dot electron pump

We have investigated the transport characteristics of an electron pump consisting of an asymmetric double quantum dot at zero bias voltage which is subject to electromagnetic radiation. Depending on the energies of the intermediate states in the pumping cycle, electrons can be transferred through the dots incoherently via sequential tunneling or coherently via co-tunneling. The dc transport through the system can be controlled by the frequency of the applied radiation. We concentrate on resonant tunneling peaks in the pumping current that are interesting to observe experimentally.

cond-mat.mes-hall↗

arXiv1997

Conductance Fluctuations in a Metallic Wire Interrupted by a Tunnel Junction

The conductance fluctuations of a metallic wire which is interrupted by a small tunnel junction has been explored experimentally. In this system, the bias voltage V, which drops almost completely inside the tunnel barrier, is used to probe the energy dependence of conductance fluctuations due to disorder in the wire. We find that the variance of the fluctuations is directly proportional to V. The experimental data are consistently described by a theoretical model with two phenomenological parameters: the phase breaking time at low temperatures and the diffusion coefficient.

cond-mat.mes-hall↗

arXiv1996

"Electro-flux" effect in superconducting hybrid Aharonov-Bohm rings

We have extended the circuit theory of Andreev conductance [Phys.~Rev.~Lett. {\bf 73}, 1420 (1994)] to diffusive superconducting hybrid structures that contain an Aharonov-Bohm ring. The electrostatic potential distribution in the system is predicted to be flux-dependent with a period of the superconducting flux quantum $Φ_{0}=h/2e$. When at least one tunnel barrier is present, the conductance of the system oscillates with the same period.

cond-mat↗

arXiv1996

Kinetic equation approach to diffusive superconducting hybrid devices

We present calculations of the temperature-dependent electrostatic and chemical potential distributions in disordered normal metal-superconductor structures. We show that they differ appreciably in the presence of a superconducting terminal and propose an experiment to measure these two different potential distributions. We also compute the resistance change in these structures due to a recently proposed mechanism which causes a finite effect at zero temperature. The relative resistance change due to this effect is of the order of the interaction parameter in the normal metal. Finally a detailed calculation of the resistance change due to the temperature dependence of Andreev reflection in diffusive systems is presented. We find that the maximal magnitude due to this thermal effect is in general much larger than the magnitude of the novel effect.

cond-mat↗

arXiv1995

Time-dependent resonant tunneling via two discrete states

We theoretically investigate time-dependent resonant tunneling via two discrete states in an experimentally relevant setup. Our results show that the dc transport through the system can be controled by applying irradiation with a frequency which matches the energy difference between the discrete states. We predict resonant phenomena which should be easily observable in experiments.

cond-mat↗

arXiv1993

Subgap Conductivity of a Superconducting-Normal Tunnel Interface

At low temperatures, the transport through a superconducting-normal tunnel interface is due to tunneling of electrons in pairs. The probability for this process is shown to depend on the layout of the electrodes near the tunnel junction, rather than on properties of the tunnel barrier. This dependence is due to interference of the electron waves on a space scale determined by the coherence length, either in the normal or the superconducting metal. The approach developed allows us to evaluate the subgap current for different layouts of interest.

cond-mat↗

arXiv1993

Interference of two electrons entering a superconductor

The subgap conductivity of a normal-superconductor (NS) tunnel junction is thought to be due to tunneling of two electrons. There is a strong interference between these two electrons, originating from the spatial phase coherence in the normal metal at a mesoscopic length scale and the intrinsic coherence of the superconductor. We evaluated the interference effect on the transport through an NS junction. We propose the layouts to observe drastic Aharonov-Bohm and Josephson effects.

cond-mat↗