Mobile impurity in one-dimensional correlated electron systems

P. Schlottmann, Andrei A. Zvyagin

Giniyat Khaliullin, S. Krivenko, Peter Fulde

A. S. Campbell, Dimitri M. Gangardt

We use a mobile impurity or depleton model to study elementary excitations in one-dimensional integrable systems. For Lieb-Liniger and bosonic Yang-Gaudin models we express two phenomenological parameters characterising renormalised inter- actions of mobile impurities with superfluid background: the number of depleted particles, $N$ and the superfluid phase drop $\pi J$ in terms of the corresponding Bethe Ansatz solution and demonstrate, in the leading order, the absence of two-phonon scattering resulting in vanishing rates of inelastic processes such as viscosity experienced by the mobile impurities

Amal Medhi, Saurabh Basu, Charudatt Kadolkar

Magnetic correlations are studied in a two-leg Hubbard ladder doped with nonmagnetic impurities using finite temperature quantum Monte Carlo (FTQMC) method. A number of relevant macroscopic quantities calculated as a function of temperature T and impurity concentration are found to exhibit significantly renormalized behavior, a feature noted in many experiments. The uniform magnetic susceptibility χ0(T) for the impurity doped system shows a cusplike behavior followed by a sharp increase at lower temperatures, signaling the formation of impurity induced free magnetic moments, while it diminishes rapidly for the pure system. The spin correlations are found to increase in the vicinity of an impurity. To investigate the effect of nonmagnetic impurities on the spin wave modes in the system, spin wave velocity vsw is calculated as a function of impurity concentration. The result shows that vsw is reduced by nonmagnetic impurities, indicating softening of the modes. Simulations are performed slightly away from half filling and kinetic energy of the electrons in the neighborhood of an impurity site is calculated to study the interplay between impurities and holes. However, contrary to previous experimental observations on two dimensional lattices where nonmagnetic impurities reduce hole mobility, no noticeable effect of impurity on the mobility of the neighboring electrons is found in our calculation.

Niaz Ali Khan

Maksims Arzamasovs, Filippo Bovo, Dimitri M. Gangardt

We examine the hydrodynamic approach to dynamical correlations in one-dimensional superfluids near integrability and calculate the characteristic time scale, τ, beyond which this approach is valid. For time scales shorter than τ, hydrodynamics fails, and we develop an approach based on kinetics of fermionic quasiparticles described as mobile impurities. New universal results for the dynamical structure factor relevant to experiments in ultracold atomic gases are obtained.