Ultrathin fiber-taper coupling with nitrogen vacancy centers in nanodiamonds at cryogenic temperatures

TL;DR

This paper reports the successful cooling of ultrathin fiber tapers coupled with nanodiamond NV centers to cryogenic temperatures, enabling potential quantum information and nanoscale magnetometry applications.

Contribution

It introduces a method to cool fiber-taper and nanodiamond NV center systems to cryogenic temperatures, demonstrating efficient fluorescence channeling and sharp zero-phonon lines.

Findings

Nanodiamonds with NV centers are deposited on 480-nm fiber tapers.

Fiber tapers are cooled to 9 K with optimized cooling.

Fluorescence shows sharp zero-phonon lines at cryogenic temperatures.

Abstract

We demonstrate cooling of ultrathin fiber tapers coupled with nitrogen vacancy (NV) centers in nanodiamonds to cryogenic temperatures. Nanodiamonds containing multiple NV centers are deposited on the subwavelength 480-nm-diameter nanofiber region of fiber tapers. The fiber tapers are successfully cooled to 9 K using our home-built mounting holder and an optimized cooling speed. The fluorescence from the nanodiamond NV centers is efficiently channeled into a single guided mode and shows characteristic sharp zero-phonon lines of both neutral and negatively charged NV centers. The present nanofiber/nanodiamond hybrid systems at cryogenic temperatures can be used as NV-based quantum information devices and for highly sensitive nanoscale magnetometry in a cryogenic environment.