Decoherence and the Thouless Crossover in One-Dimensional Conductors

The temperature and magnetic-field dependences of the resistance of one-dimensional (1D) conductors have been studied in the vicinity of the Thouless crossover. We find that on the weak localization (WL) side of the crossover, these dependences are consistent with the theory of quantum corrections to the resistance, and the phase breaking is due to the quasi-elastic electron-electron interactions (the Nyquist noise). The temperature dependence of the phase coherence time does not saturate, and the quasiparticle states remain well defined over the whole WL temperature range. This fact, as well as observation of the Thouless crossover in 1D samples, argues against the idea of intrinsic decoherence by zero-point fluctuations of the electrons (Mohanty et al., Phys.Rev.Lett. 78, 3366 (1997)). We believe that frequently observed saturation of the phase coherence time is caused by the external microwave noise.