  Creating macroscopic spatial quantum superposition with a nanoparticle has a
multitude of applications, ranging from testing the foundations of quantum
mechanics, matter-wave interferometer for detecting gravitational waves and
probing the electromagnetic vacuum, dark matter detection and quantum sensors
to testing the quantum nature of gravity in a lab. In this paper, we
investigate the role of rotation in a matter-wave interferometer, where we show
that imparting angular momentum along the direction of a defect, such as one
present in the nitrogen-vacancy centre of a nanodiamond can cause an
enhancement in spin contrast for a wide-ranging value of the angular momentum,
e.g. $10^{3}-10^{6}$~Hz for a mass of order $10^{-14}-10^{-17}$ Kg nanodiamond.
Furthermore, the imparted angular momentum can enhance the spatial
superposition by almost a factor of two and possibly average out any potential
permanent dipoles in the nanodiamond.
