Massive quantum superpositions using magneto-mechanics

TL;DR

This paper proposes two schemes to create large quantum superpositions of massive objects using magnetic forces, enabling superpositions vastly larger than zero-point motion, with potential applications in quantum sensing and fundamental physics.

Contribution

It introduces novel magneto-mechanical methods for generating macroscopic quantum superpositions with high spatial extent, independent of particle size.

Findings

Large superpositions ($ imes 10^6$ zero-point motion) are achievable.

Superpositions are generated via magnetic forces on flux qubits and levitated magnets.

Methods are robust for massive quantum oscillator systems.

Abstract

Macroscopic quantum superpositions of massive objects are deeply interesting as they have a number of potential applications ranging from the exploration of the interaction of gravity with quantum mechanics to quantum sensing, quantum simulation, and computation. In this letter, we propose two related schemes to prepare a spatial superposition of massive quantum oscillator systems with high Q-factor via a superposition of magnetic forces. In the first method, we propose a large spatial superposition of a levitated spherical magnet generated via magnetic forces applied by adjacent flux qubits. We find that in this method the spatial superposition extent ($\Delta z$) is independent of the size of the particle. In the second method, we propose a large spatial superposition of a magnetically levitated (using the Meissner effect) flux qubit, generated via driving the levitated qubit inductively. In both schemes, we show that ultra-large superpositions $\Delta z/\delta z_{\rm zpm}\sim 10^6$, are possible, where $\delta z_{\rm zpm}$ is the zero point motional extent.