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

Abstract

We study spin relaxation and decoherence in nanotube quantum dots 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 T1 exceeding tens of seconds. For small phonon frequencies ω, we find a 1/ √ ω spin-phonon noise spectrum -a dissipation channel for spins in quantum dots -which can reduce T1 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.

Spin-orbit effects in carbon-nanotube double quantum dots

“…Its origin is not well understood for now, and it is usually attributed to electron scattering by defects. 34 Next, we discuss the longitudinal part of the wave function ͑t͒ and begin with exact symmetries of wave functions. Substituting Eq.…”

“…The demonstration of electrostatically confined particles in CNT-QDs in the presence of SO coupling 18,20 has motivated recent theoretical investigations. The single-electron QD setup and, in particular, the influence of the electron-phonon coupling on the decoherence are subjects of a work by Bulaev et al 34 The two-particle problem has been studied numerically in Refs. 35 and 36 for a hard wall and a harmonic potential, respectively.…”

Coupling of spin and orbital motion of electrons in carbon nanotubes

“…2d) An interesting prediction of the theory 12,13,18 is the breaking of electron-hole symmetry. In the absence of SO interactions the low-energy spectrum of a NT exhibits electron-hole symmetry such that each allowed state has a matching state with opposite energy; i.e., the spectrum is symmetric upon reflection about the line 0 = E .…”

“…Our measurements are consistent with recent theories 12,13 that predict the existence of spin-orbit coupling in curved graphene and describe it as a spin-dependent topological phase in NTs. Our findings have important implications for spin-based applications in carbon-based systems, entailing new design principles for the realization of qubits in NTs and providing a mechanism for all-electrical control of spins 14 in NTs.Carbon-based systems are promising candidates for spin based applications such as spinqubits [14][15][16][17][18][19] and spintronics 20-23 as they are believed to have exceptionally long spin coherence times due to weak spin-orbit interactions and the absence of nuclear spin in the 12 C atom. Carbon NTs may play a particularly interesting role in this context because in addition to spin they offer a unique two-fold orbital degree of freedom that can also be used for quantum manipulation.…”

“…Carbon-based systems are promising candidates for spin based applications such as spinqubits [14][15][16][17][18][19] and spintronics [20][21][22][23] as they are believed to have exceptionally long spin coherence times due to weak spin-orbit interactions and the absence of nuclear spin in the 12 C atom. Carbon NTs may play a particularly interesting role in this context because in addition to spin they offer a unique two-fold orbital degree of freedom that can also be used for quantum manipulation.…”