arXiv subjects

A. Posazhennikova

Publications and source records attributed to A. Posazhennikova.

3 recordsLinked to original sources

arXiv2010

Phonon resonances in atomic currents through Bose-Fermi mixtures in optical lattices

We present an analysis of Bose-Fermi mixtures in optical lattices for the case where the lattice potential of the fermions is tilted and the bosons (in the superfluid phase) are described by Bogoliubov phonons. It is shown that the Bogoliubov phonons enable hopping transitions between fermionic Wannier-Stark states; these transitions are accompanied by energy dissipation into the superfluid and result in a net atomic current along the lattice. We derive a general expression for the drift velocity of the fermions and find that the dependence of the atomic current on the lattice tilt exhibits negative differential conductance and phonon resonances. Numerical simulations of the full dynamics of the system based on the time-evolving block decimation algorithm reveal that the phonon resonances should be observable under the conditions of a realistic measuring procedure.

cond-mat.quant-gas↗

arXiv2004

Singular conductance of a spin 1 quantum dot

We interpret the recent observation of a zero-bias anomaly in spin-1 quantum dots in terms of an underscreened Kondo effect. Although a spin-1 quantum dots are expected to undergo a two-stage quenching effect, in practice the log normal distribution of Kondo temperatures leads to a broad temperature region dominated by underscreened Kondo physics. General arguments, based on the asymptotic decoupling between the partially screened moment and the leads, predict a singular temperature and voltage dependence of the conductance $G$ and differential conductance $g$, resulting in $dg/dT\sim 1/T$ and $dG/dV \sim 1/V$. Using a Schwinger boson approach, we show how these qualitative expectations are borne out in a detailed many body calculation.

cond-mat.mes-hall↗

arXiv2003

Quenched disorder formulation of the pseudo-gap problem

The problem of pseudo-gap formation in an electronic system, induced by the fluctuations of the order parameter is revisited. We make the observation that a large class of current theories are theoretically equivalent to averaging the Free energy of the pseudo-gap system over a quenched-disordered distribution of the order parameter. We examine the cases of both infinite and finite correlation length, showing how the interplay of pseudo-gap formation and superconductivity can be treated in this approach.

cond-mat.str-el↗