title: Burning and graphitization of optically levitated nanodiamonds in vacuum.
abstract: A nitrogen-vacancy (NV(-)) centre in a nanodiamond, levitated in high vacuum, has recently been proposed as a probe for demonstrating mesoscopic centre-of-mass superpositions and for testing quantum gravity. Here, we study the behaviour of optically levitated nanodiamonds containing NV(-) centres at sub-atmospheric pressures and show that while they burn in air, this can be prevented by replacing the air with nitrogen. However, in nitrogen the nanodiamonds graphitize below ≈10 mB. Exploiting the Brownian motion of a levitated nanodiamond, we extract its internal temperature (T(i)) and find that it would be detrimental to the NV(-) centre's spin coherence time. These values of T(i) make it clear that the diamond is not melting, contradicting a recent suggestion. Additionally, using the measured damping rate of a levitated nanoparticle at a given pressure, we propose a new way of determining its size.
authors.affiliation: Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT, UK.|Department of Physics, University of Warwick, Gibbet Hill Road, CV4 7AL, UK.
authors.forename: A T M A
authors.initials: AT
authors.lastname: Rahman
authors.affiliation: Department of Physics, University of Warwick, Gibbet Hill Road, CV4 7AL, UK.
authors.forename: A C
authors.initials: AC
authors.lastname: Frangeskou
authors.affiliation: QOLS, Blackett Laboratory, Imperial College London, SW7 2BW, UK.
authors.forename: M S
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT, UK.
authors.forename: S
authors.initials: S
authors.lastname: Bose
authors.affiliation: Department of Physics, University of Warwick, Gibbet Hill Road, CV4 7AL, UK.
authors.forename: G W
authors.initials: GW
authors.lastname: Morley
authors.affiliation: Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT, UK.
authors.forename: P F
authors.initials: PF
authors.lastname: Barker