title: Ultrathin fiber-taper coupling with nitrogen vacancy centers in nanodiamonds 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 (ZPLs) 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.
authors.forename: Masazumi
authors.initials: M
authors.lastname: Fujiwara
authors.forename: Hong-Quan
authors.initials: HQ
authors.lastname: Zhao
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Noda
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ikeda
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sumiya
authors.forename: Shigeki
authors.initials: S
authors.lastname: Takeuchi