Spin-orbit interaction and anomalous spin relaxation in carbon nanotube quantum dots

Abstract

We study spin relaxation and decoherence caused by electron-lattice and spin-orbit interaction and predict striking effects induced by magnetic fields $B$. For particular values of $B$, destructive interference occurs resulting in ultralong spin relaxation times $T_1$ exceeding tens of seconds. For small phonon frequencies $ω$, we find a $1/\sqrtω$ spin-phonon noise spectrum -- a novel dissipation channel for spins in quantum dots -- which can reduce $T_1$ by many orders of magnitude. We show that nanotubes exhibit zero-field level splitting caused by spin-orbit interaction. This enables an all-electrical and phase-coherent control of spin.

19 pages, 12 figures