On-chip quantum interference of a superconducting microsphere

TL;DR

This paper proposes a magnetically levitated superconducting microsphere experiment to demonstrate quantum interference at a macroscopic scale, potentially testing gravitational decoherence models.

Contribution

It introduces a novel all-magnetic scheme for quantum superposition and interferometry of a superconducting microsphere, enabling earth-based tests of gravitational decoherence.

Findings

Feasible preparation of a spatial quantum superposition of a microsphere.

Potential to falsify gravitationally-induced decoherence models.

Implementation of fast quantum interferometry using quantum magnetomechanics.

Abstract

We propose and analyze an all-magnetic scheme to perform a Young's double slit experiment with a micron-sized superconducting sphere of mass $\gtrsim {10}^{13}$ amu. We show that its center of mass could be prepared in a spatial quantum superposition state with an extent of the order of half a micrometer. The scheme is based on magnetically levitating the sphere above a superconducting chip and letting it skate through a static magnetic potential landscape where it interacts for short intervals with quantum circuits. In this way, a protocol for fast quantum interferometry using quantum magnetomechanics is passively implemented. Such a table-top earth-based quantum experiment would operate in a parameter regime where gravitational energy scales become relevant. In particular, we show that the faint parameter-free gravitationally-induced decoherence collapse model, proposed by Di\'osi and Penrose, could be unambiguously falsified.