Tuesday, November 22, 2016

Cooperatively enhanced dipole forces from artificial atoms in trapped nanodiamonds

Mathieu L. Juan, Carlo Bradac, Benjamin Besga, Mattias Johnsson, Gavin Brennen, Gabriel Molina-Terriza & Thomas Volz
Optical trapping is a powerful tool to manipulate small particles, from micrometre-size beads in liquid environments1 to single atoms in vacuum2. The trapping mechanism relies on the interaction between a dipole and the electric field of laser light. In atom trapping, the dominant contribution to the associated force typically comes from the allowed optical transition closest to the laser wavelength, whereas for mesoscopic particles it is given by the polarizability of the bulk material. Here, we show that for nanoscale diamond crystals containing a large number of artificial atoms, nitrogen–vacancy colour centres, the contributions from both the nanodiamond and the colour centres to the optical trapping strength can be simultaneously observed in a noisy liquid environment. For wavelengths around the zero-phonon line transition of the colour centres, we observe a 10% increase of overall trapping strength. The magnitude of this effect suggests that due to the large density of centres, cooperative effects between the artificial atoms contribute to the observed modification of the trapping strength. Our approach may enable the study of cooperativity in nanoscale solid-state systems and the use of atomic physics techniques in the field of nano-manipulation.

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