Disorder-induced splitting in quasiparticle interference of Bi2Te3 Dirac electrons

Inelastic interactions of quantum systems with environment usually wash coherent effects out. In the case of Friedel oscillations, the presence of disorder leads to a fast decay of the oscillation amplitude. Here we show both experimentally and theoretically that in the three-dimensional topological insulator Bi2Te3 the finite lifetime of the Dirac electrons due to disorder causes a splitting of coherent scattering vectors which follows a peculiar evolution in energy. Not only this splitting enables evaluating the lifetime of Dirac quasiparticles in topological insulators, but this general phenomenon can be in play in other quantum systems, leading to non-trivial modifications of their coherent properties.