Jonathan Lux

Hydrodynamic long-time tails after a quantum quench

After a quantum quench, a sudden change of parameters, generic many particle quantum systems are expected to equilibrate. A few collisions of quasiparticles are usually sufficient to establish approximately local equilibrium. Reaching global equilibrium is, however, much more difficult as conserved quantities have to be transported for long distances to build up a pattern of fluctuations characteristic for equilibrium. Here we investigate the quantum quench of the one-dimensional bosonic Hubbard model from infinite to finite interaction strength U using semiclassical methods for weak, and exact diagonalization for strong quenches. Equilibrium is approached only slowly, as t^{-1/2} with subleading corrections proportional to t^{-3/4}, consistent with predictions from hydrodynamics. We show that these long-time tails determine the relaxation of a wide range of physical observables.

Revealing puddles of electrons and holes in compensated topological insulators

N. Borgwardt, J. Lux, I. Vergara, Zhiwei Wang, A.A. Taskin, Kouji Segawa, P.H.M. van Loosdrecht, Yoichi Ando, 3 A. Rosch, and M. Grüninger∗1 II. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan (Dated: August 13, 2015)

Charge puddles in the bulk and on the surface of the topological insulator BiSbTeSe2 studied by scanning tunneling microscopy and optical spectroscopy

The topological insulator BiSbTeSe

Gigantic negative magnetoresistance in the bulk of a disordered topological insulator

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Length scale of puddle formation in compensation-doped semiconductors and topological insulators

corresponds to a compensated semiconductor in which strong Coulomb disorder gives rise to the formation of charge puddles, i.e., local accumulations of charge carriers, both in the bulk and on the surface. Bulk puddles are formed if the fluctuations of the Coulomb potential are as large as half of the band gap. The gapless surface, in contrast, is sensitive to small fluctuations but the potential is strongly suppressed due to the additional screening channel provided by metallic surface carriers. To study the quantitative relationship between the properties of bulk puddles and surface puddles, we performed infrared transmittance measurements as well as scanning tunneling microscopy measurements on the same sample of BiSbTeSe

Kinetic theory of Coulomb drag in two monolayers of graphene: from the Dirac point to the Fermi liquid regime

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Suppression of Quasiparticle Scattering Signals in Bilayer Graphene Due to Layer Polarization and Destructive Interference

, which is close to perfect compensation. At 5.5 K, we find surface potential fluctuations occurring on a length scale

On the metamorphoses of Maxwell's equations during the last 150 years — spotlights on the history of classical electrodynamics

r_s = 40-50

Quench dynamics and statistics of measurements for a line of quantum spins in two dimensions

nm with amplitude

Screening length in compensation-doped semiconductors and topological insulators

\Gamma = 8-14