Quantum control of Nitrogen-Vacancy spin in Diamonds: Towards matter-wave interferometry with massive objects

TL;DR

This paper discusses quantum control of nitrogen-vacancy spins in diamonds as a step towards matter-wave interferometry with massive objects, aiming to test fundamental physics principles and the quantum-gravity interface.

Contribution

It presents methods for quantum control of NV spins in nanodiamonds, enabling potential matter-wave interferometry with levitated diamonds for fundamental physics tests.

Findings

Spin coherence times of tens of microseconds are achievable in nanodiamonds.

Simulations indicate nanometer-scale spatial splitting is possible with current technology.

The work supports the feasibility of using nanodiamonds for matter-wave interferometry.

Abstract

Quantum mechanics (QM) and General relativity (GR), also known as the theory of gravity, are the two pillars of modern physics. A matter-wave interferometer with a massive particle can test numerous fundamental ideas, including the spatial superposition principle - a foundational concept in QM - in previously unexplored regimes. It also opens the possibility of probing the interface between QM and GR, such as testing the quantization of gravity. Consequently, there exists an intensive effort to realize such an interferometer. While several approaches are being explored, we focus on utilizing nanodiamonds with embedded spins as test particles which, in combination with Stern-Gerlach forces, enable the realization of a closed-loop matter-wave interferometer in space-time. There is a growing community of groups pursuing this path [1]. We are posting this technical note (as part of a series of seven such notes), to highlight our plans and solutions concerning various challenges in this ambitious endeavor, hoping this will support this growing community. Here we present our work on quantum control of a nitrogen-vacancy spin system in bulk diamonds and in levitated diamonds as a step towards Stern-Gerlach interferometry with levitated nanodiamonds. Our simulations show that the current state of the art for spin coherence time in nanodiamonds of a few tens of microseconds, is good enough to enable an SGI spatial splitting on the order of nanometers for an ND composed of 10^7 atoms. We would be happy to make available more details upon request.