Dephasing in Rashba spin precession along multichannel quantum wires and nanotubes

Coherent Rashba spin precession along interacting multimode quantum channels is investigated, revisiting the theory of coupled Tomonaga-Luttinger liquids. We identify susceptibilities as the key parameters to govern exponents and Rashba precession lengths. In semiconducting quantum wires spins of different transport channels are found to dephase in their respective precession angles with respect to one another, as a result of the interaction. This could explain the experimental difficulty to realize the Datta Das transistor. In single walled carbon nanotubes, on the other hand, interactions are predicted to suppress dephasing between the two flavor modes at small doping.

Figure 1

Difference $\mid {\lambda }_2-{\lambda }_1\mid ∕{\lambda }^{\left(0\right)}$ vs Fermi energy ${ϵ}_F∕{\omega }_0$ in units of the subband energy ${\omega }_0$ for two channels. In QW (a) interactions always cause dephasing between both modes while in single walled NT (b) dephasing between the two flavor modes can be significantly suppressed at small doping compared to the noninteracting case (dashed).