Trapping and cooling of nanodiamonds in a Paul trap under ultra-high vacuum: Towards matter-wave interferometry with massive objects

TL;DR

This paper reports on trapping and cooling nanodiamonds in a Paul trap under ultra-high vacuum conditions, advancing the development of matter-wave interferometry with massive objects to test fundamental physics principles.

Contribution

It presents a detailed methodology for trapping and cooling nanodiamonds in a Paul trap under ultra-high vacuum, supporting future matter-wave interferometry experiments with massive particles.

Findings

Successfully trapped nanodiamonds at 10^-8 mbar

Achieved sub-Kelvin cooling of nanodiamonds

Nanodiamonds remained confined under high-intensity laser illumination

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. In this work we detail the trapping of a nanodiamond at 10^-8 mbar, which is good enough for the realization of a short-duration Stern-Gerlach interferometer. We describe in detail the cooling we have performed to sub-Kelvin temperatures, and demonstrate that the nanodiamond remains confined within the trap even under high-intensity 1560 nm laser illumination. We would be happy to make available more details upon request.