Low-energy quasiparticle transport through Andreev levels

Superlattices and Microstructures

We use a semiclassical approach for analysing the tunneling transport through a normal conductor in contact with superconducting mirrors. Our analysis of the electron-hole propagation along semiclassical trajectories shows that resonant transmission through Andreev levels is possible resulting in an excess, low-energy quasiparticle contribution to the conductance. The excess conductance oscillates with the phase difference between the superconductors having maxima at odd multiples of $\pi$ for temperatures much below the Thouless temperature Comment: 12 pages, 3 figures; submitted to a special volume of Superlattices and Microstructures on Mesoscopic Superconductivity

Physical Review B, 1998

Physical Review Letters, 2001

We have performed the tunnel spectroscopy of the energy distribution function of quasiparticles in 5-mm-long silver wires connected to superconducting reservoirs biased at different potentials. The distribution function f͑E͒ presents several steps, which are manifestations of multiple Andreev reflections at the NS interfaces. The rounding of the steps is well explained by electron-electron interactions.

Physical Review B, 2009

We analyze the non-local transport properties of a d-wave superconductor coupled to metallic electrodes at nanoscale distances. We show that the non-local conductance exhibits an algebraical decay with distance rather than the exponential behavior which is found in conventional superconductors. Crossed Andreev processes, associated with electronic entanglement, are favored for certain orientations of the symmetry axes of the superconductor with respect to the leads. These properties would allow its experimental detection using present technologies.

Phys Rev B, 1997

We present experiments revealing a singularity in the coherent current across a superconductor/ semiconductor/superconductor ͑SSmS͒ junction at the bias voltage corresponding to the superconducting energy gap Vϭ⌬/e. The SSmS structure consists of highly doped GaAs with superconducting electrodes of aluminum configured as an interferometer. The phase-coherent component of the current is probed as the amplitude of h/2e vs magnetic-field oscillations in the differential resistance of the interferometer.

Journal of Computational and Theoretical Nanoscience, 2008

We have investigated the quantum transport through the Superconductor-Semiconductor mesoscopic interface in the presence of an external radiation field. The current spectrum is analyzed as a function of the frequency and the temperature. The current-voltage (I-V) characteristics were found to be very sensitive to the photon frequency. Additionally, photon-assisted transport in our system is very robust: The one-photon channel remains up to low temperature, which implies that these structures support gain at THz frequencies even at 9 K. The resonances sit on a background current which it is deeply modified, as a result of photon assisted multiple Andreev reflections. The results render rigid support for the full quantum theory of transport between two superconductors based on the idea of Andreev bound states.

Physical Review B, 1997

We present experiments revealing a singularity in the coherent current across a superconductor/ semiconductor/superconductor ͑SSmS͒ junction at the bias voltage corresponding to the superconducting energy gap Vϭ⌬/e. The SSmS structure consists of highly doped GaAs with superconducting electrodes of aluminum configured as an interferometer. The phase-coherent component of the current is probed as the amplitude of h/2e vs magnetic-field oscillations in the differential resistance of the interferometer.

Phys Rev B, 1997

We present experiments revealing a singularity in the coherent current across a superconductor/semiconductor/superconductor (SSmS) junction at the bias voltage corresponding to the superconducting energy gap V=Δ/e. The SSmS structure consists of highly doped GaAs with superconducting electrodes of aluminum configured as an interferometer. The phase-coherent component of the current is probed as the amplitude of h/2e vs magnetic-field oscillations in the differential resistance of the interferometer.

Physica B: Condensed Matter, 1998

Physical Review B, 2014

Phase-and voltage bias-sensitive quasiparticle transport at a double N IS1IS2 interface is considered. The barriers I range from tunnel to transparent, and the intermediate region S1 has a width comparable to the superconducting coherence length. A phase difference ϕ is applied to the Josephson junction S1IS2. The normal and Andreev reflections at the N IS1 interface become ϕ-sensitive, and transport is governed by interferences within the narrow S1 region, both in the normal and anomalous channels. The subgap conductance is separately (energy E)-and (phase ϕ)symmetric. Above the superconducting gap, the conductance is in general not symmetric even if (E, ϕ) is changed in (−E, −ϕ), but the symmetry is restored by averaging Fermi oscillations. The Tomasch oscillations are amplified by the phase difference. The subgap conductance exhibits a resonant structure at the energy of the Andreev bound states (ABS) of the S1IS2 junction, providing a side-spectroscopy of such states. Depending on the relative transparencies of the junctions, the resonance can increase or reduce the conductance, and it can even vanish for ϕ = π, featuring total reflection of quasiparticles at N S1 by the ABS at S1S2.