Intrinsic phase-decoherence of electrons by two-level systems

Abstract

The fundamental problem of the phase saturation of electrons in a disordered mesoscopic system at very low temperatures is addressed. The disorder in the medium has both static and dynamic components, the latter being in the form of two-level systems (TLSs) which become just about the only source of inelastic scattering in the limit T → 0. We propose that besides the inelastic nature of scattering from the TLSs, the phase shift of the electrons is also affected by the nature of tunneling in the TLSs. The tunneling becomes incoherent as T decreases due to increasing long-range interactions among the TLSs which affects the phase coherence of electrons scattering from them. The competition between this effect, which increases as ∼ T-1, and that of the scattering rate τe-TLS-1 behaving as ∼ T apparently govern the phase shift of the electrons.