We propose a current-carrying-chip scheme for generating spatial quantum superpositions using a levitating nanodiamond with a built-in nitrogen-vacancy (NV) centre defect. Our setup is quite versatile and we aim to create the superposition for a mass range of 10−19kg<m<10−15kg and a superposition size O(10)μm<Δx<O(1)nm, respectively, in t≤0.1s, depending on the position we launch from the center of the diamagnetic trap. We provide an in-depth analysis of two parallel chips that can create levitation and spatial superposition along the x-axis, while producing a very tight trap in the y direction, and the direction of gravity, i.e., the z direction. Numerical simulations demonstrate that our setup can create a one-dimensional spatial superposition state along the x-axis. Throughout this process, the particle is stably levitated in the z-direction, and its motion is effectively confined in the y-direction for a Gaussian initial condition. This setup presents a viable platform for a diamagnetically levitated nanoparticle for a table-top experiment exploring the possibility of creating a macroscopic Schr\"odinger Cat state to test the quantum gravity induced entanglement of masses (QGEM) protocol.
@article{arxiv.2601.06608,
title = {Magnetic levitation and spatial superposition of a nanodiamond with a current-carrying chip},
author = {Qian Xiang and Shafaq Gulzar Elahi and Andrew Geraci and Sougato Bose and Anupam Mazumdar},
journal= {arXiv preprint arXiv:2601.06608},
year = {2026}
}