Orbital hyperfine interaction and qubit dephasing in carbon nanotube quantum dots

Csiszár, Gábor and Pályi, András (2014) Orbital hyperfine interaction and qubit dephasing in carbon nanotube quantum dots. PHYSICAL REVIEW B, 90 (24). ISSN 2469-9950

Preview

Text 1409.2756.pdf Available under License Creative Commons Attribution. Download (954kB) | Preview

Abstract

Hyperfine interaction (HF) is of key importance for the functionality of solid-state quantum information processing, as it affects qubit coherence and enables nuclear-spin quantum memories. In this work, we complete the theory of the basic HF mechanisms (Fermi contact, dipolar, orbital) in carbon nanotube quantum dots by providing a theoretical description of the orbital HF. We find that orbital HF induces an interaction between the nuclear spins of the nanotube lattice and the valley degree of freedom of the electrons confined in the quantum dot. We show that the resulting nuclear-spin-electron-valley interaction (i) is approximately of Ising type; (ii) is essentially local, in the sense that a radius- and dot-length-independent atomic interaction strength can be defined; and (iii) has an atomic interaction strength that is comparable to the combined strength of the Fermi contact and dipolar interactions. We argue that orbital HF provides a new decoherence mechanism for single-electron valley qubits and spin-valley qubits in a range of multivalley materials. We explicitly evaluate the corresponding inhomogeneous dephasing time T2∗ for a nanotube-based valley qubit.

Actions (login required)

Edit Item