[Paper Review] Magnetic Skatepark for Quantum Interference of a Superconducting Microsphere

H. Pino, Jordi Prat‐Camps+3 more|arXiv (Cornell University)|Mar 4, 2016

Quantum Mechanics and Applications3 citations

TL;DR

This paper proposes a table-top experiment using magnetic levitation and quantum circuits to create a spatial quantum superposition of a superconducting microsphere (~10^13 amu), enabling fast quantum interferometry via a magnetic skatepark. The scheme tests the Diosi-Penrose gravitationally-induced decoherence model, offering a potential falsification in a regime where gravitational energy scales are relevant.

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 Diosi and Penrose, could be unambiguously falsified.

Motivation & Objective

• To realize a table-top quantum interference experiment with a massive superconducting microsphere using magnetic levitation.
• To explore the role of gravitational energy scales in quantum decoherence using a macroscopic quantum system.
• To test the parameter-free gravitationally-induced decoherence model of Diosi and Penrose in a laboratory setting.
• To implement fast quantum interferometry via passive coupling to quantum circuits in a magnetic potential landscape.

Proposed method

• Magnetic levitation suspends a superconducting microsphere above a superconducting chip, enabling stable quantum motion in the center-of-mass degree of freedom.
• A static magnetic potential landscape is engineered to guide the microsphere through a double-slit-like configuration, creating a spatial superposition.
• Short, controlled interactions with quantum circuits are used to entangle the microsphere's center of mass with qubits, enabling interferometric measurement.
• The system operates in a parameter regime where gravitational energy scales become significant, making it sensitive to gravity-inspired decoherence models.
• The protocol leverages quantum magnetomechanics to passively implement interferometry without active control during the superposition evolution.
• Theoretical analysis shows that the scheme is robust against decoherence and feasible with current superconducting circuit technology.

Experimental results

Research questions

• RQ1 Can a superconducting microsphere of mass ~10^13 amu be prepared in a spatial quantum superposition of ~0.5 µm extent using magnetic levitation?
• RQ2 Is it possible to perform fast quantum interferometry on such a massive object using passive coupling to quantum circuits?
• RQ3 Can the proposed setup unambiguously falsify the Diosi-Penrose model of gravitationally-induced decoherence?
• RQ4 What is the role of gravitational energy scales in the decoherence dynamics of macroscopic quantum superpositions in this setup?
• RQ5 How does the magnetic skatepark potential landscape enable controlled, coherent evolution of the microsphere's center of mass?

Key findings

• The superconducting microsphere can be prepared in a spatial quantum superposition with an extent of approximately half a micrometer, consistent with the requirements for testing macroscopic quantum effects.
• The scheme enables fast quantum interferometry through passive coupling to quantum circuits, avoiding active control during superposition evolution.
• The experiment operates in a parameter regime where gravitational energy scales are relevant, making it sensitive to gravity-inspired decoherence models.
• The faint parameter-free gravitationally-induced decoherence model of Diosi and Penrose can be unambiguously falsified by this setup.
• The magnetic skatepark design ensures robustness against decoherence and is realizable with existing superconducting circuit and nanofabrication technology.