title: Electron spin control of optically levitated nanodiamonds in vacuum.
abstract: Electron spins of diamond nitrogen-vacancy (NV) centres are important quantum resources for nanoscale sensing and quantum information. Combining NV spins with levitated optomechanical resonators will provide a hybrid quantum system for novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centres in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this system, we investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect. We also observe that oxygen and helium gases have different effects on both the photoluminescence and the ESR contrast of nanodiamond NV centres, indicating potential applications of NV centres in oxygen gas sensing. Our results pave the way towards a levitated spin-optomechanical system for studying macroscopic quantum mechanics.
authors.affiliation: Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Thai M
authors.initials: TM
authors.lastname: Hoang
authors.affiliation: School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Jonghoon
authors.initials: J
authors.lastname: Ahn
authors.affiliation: School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Jaehoon
authors.initials: J
authors.lastname: Bang
authors.affiliation: Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA.|School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA.|Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA.|Purdue Quantum Center, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Tongcang
authors.initials: T
authors.lastname: Li