Spin dynamical decoupling for generating macroscopic superpositions of a free-falling nanodiamond
Benjamin D. Wood, Sougato Bose, Gavin W. Morley
Abstract
Levitated nanodiamonds containing negatively charged nitrogen-vacancy centers $({\text{NV}}^{\ensuremath{-}})$ have been proposed as a platform to generate macroscopic spatial superpositions. Requirements for this include having a long ${\text{NV}}^{\ensuremath{-}}$ spin coherence time, which necessitates formulating a dynamical decoupling strategy in which the regular spin flips do not cancel the growth of the superposition through the Stern-Gerlach effect in an inhomogeneous magnetic field. Here, we propose a scheme to place a $250\text{\ensuremath{-}}\mathrm{n}\mathrm{m}$-diameter diamond in a superposition with spatial separation of over $250\phantom{\rule{0.16em}{0ex}}\mathrm{n}\mathrm{m}$, while incorporating dynamical decoupling. We achieve this by letting a diamond fall for $2.4\phantom{\rule{0.16em}{0ex}}\mathrm{m}$ through a magnetic structure, including $1.13\phantom{\rule{0.16em}{0ex}}\mathrm{m}$ in an inhomogeneous region generated by magnetic teeth.