Magnetic levitation and spatial superposition of a nanodiamond with a current-carrying chip

TL;DR

This paper proposes a versatile chip-based scheme to levitate and generate spatial quantum superpositions of nanodiamonds with NV centers, enabling potential tests of macroscopic quantum phenomena and quantum gravity effects.

Contribution

It introduces a novel current-carrying chip setup for creating and controlling spatial superpositions of levitated nanodiamonds, advancing experimental capabilities for macroscopic quantum states.

Findings

Numerical simulations confirm the creation of one-dimensional spatial superpositions.

The setup achieves stable levitation and confinement in multiple directions.

Superposition sizes of up to 10 micrometers are feasible within 0.1 seconds.

Abstract

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 $10^{-19}~{\rm kg}< m< 10^{-15}~{\rm kg}$ and a superposition size ${\cal O}(10) {\rm \mu m} < \Delta x < {\cal O}(1){\rm nm}$, respectively, in $t\leq 0.1$s, 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.