Optomechanics using localized excitons in suspended carbon nanotubes

Abstract

Carbon nanotubes have generated a huge research interest in the last two decades. It can be seen as a wire with a diameter of about 1 nm. Because of this reduced dimensionality, nanotubes offer unique scientific and technological opportunities as nanomechanical resonators. Such resonators pave the way for new sensing applications with unprecedented sensitivities. The linewidth of localized excitons in semiconducting carbon nanotubes was recently demonstrated to be very narrow (<10 GHz). Once localized by an external potential or a defect, excitonic states combine long coherent times (10 ns) and bright emission lines. It is likely that excitons and the local mechanical stress are strongly coupled in carbon nanotubes, so that localized excitons are promising to up convert the mechanical motion to optical fields. Coupling the mechanical motion of a nanotube to excitons is appealing: it holds promise for the detection of ultra-small displacements. Interestingly, in this limit, the physics is governed by the laws of quantum mechanics. We study photoluminescence of ultra-clean suspended carbon nanotubes at low temperature and we propose original scheme to measure the mechanical vibration via the exciton lineshift.