Correlated dynamics of quantum wires and cigar shaped atomic gases

In one- dimensional Fermi systems the elementary excitations,as predicted by Tomonaga- Luttinger liquid (TLL) theory, are spin and charge density waves, traveling at different velocities (the spin velocity is smaller, the charge velocity greater than the Fermi velocity). These velocities are parameters of <br>the TLL theory and there is no straightforward way to extract them from the parameters of a microscopic model. <br>But by exploiting the equivalence of the TLL ground state with the <br>usual electron ground state we are able to extract them from <br>the microscopic model's ground state energy. <br> <br>In this work we investigate the dependence of charge and spin dynamics <br>on the interactions in different manifestations of 1D Fermi systems. <br>We are especially interested in the system's spin sector, which, <br>contrary to folklore, gets modified by electron- electron interactions. <br>To do so we describe the system's dynamics in terms of the TLL <br>while we model the interacting system's ground state with electron gas <br>techniques. <br> <br>In quantum wires we use thermodynamical relations to obtain <br>the plasmon and magnon velocities from the microscopic model <br>and find out that the ladder approximation (LA) to the <br>interaction vertex faithfully follows quantum Monte Carlo data while <br>using a fraction of the processor time; other mean field methods, <br>although sometimes superior to the LA in the charge sector fail <br>to give meaningful results in the spin sector. <br> <br>We also study the interplay of contact interaction and containment in <br>atomic traps, where we found out that the vanishing spin velocity <br>(proportional to density squared) at low densities, as predicted from Bethe <br>ansatz calculation, leads to a giant spin- charge separation; namely <br>charge density waves get reflected at the system's edge while spin density <br>waves experience an exponential slowing down and don't get reflected at the <br>trap edge.

Author dc:creator

• Kecke, Lars

Contributors dc:contributor

• Grabert, Hermann

• Luttinger liquid

Repository record source_url

https://freidok.uni-freiburg.de/data/2007

OAI identifier oai:identifier

oai:freidok.uni-freiburg.de:2007