ERA-NET_NanoSci-E+ 1. Call_NOIs

We aim to use optical nanofibres for interfacing, manipulating, and controlling nano-particles with light. Such nanofibres will be integrated into novel environments, including ion traps, cold atom traps, and optical tweezers. We will experimentally investigate the coupling of a single or few ions with the evanescent field of an optical nanofibre and explore the possibility to trap ions in the vicinity of the evanescent field. On the theory side, the collective coupling of ions or atoms trapped close to a nanofibre via evanescent fields will be modelled. Furthermore, using higher order optical modes, we aim to tailor the evanescent field and to study the optical binding of complex three dimensional arrays of colloidal particles in the vicinity of the nanofibre as well as their response to transfer of angular momentum. Finally, we will consider the feasibility of trapping neutral atoms in the evanescent field of a guided nanofibre mode exhibiting a complex polarisation pattern.

There are numerous applications for which light is guided inside optical glass fibres. However, when standard optical fibres are drawn to be only a few hundred nanometres thick - less than the wavelength of light - the light is still guided by the fibre, but it is no longer confined to be within the fibre: the light field extends several hundred nanometres outside the fibre. This light can then interact with particles - such as atoms or ions - which are nearby. Experimentally, this project aimed to bring individual atomic ions close to a nanofibre. Holding the ions with radio-frequency electric fields, they were brought within a few tens of micrometres of the nanofibre. This is the first time ions have been trapped in proximity to a nanofibre, and the closest they have ever been trapped to a macro- or mesoscopic object. In parallel, theory work was carried out to investigate what would happen if multiple ions (or similar objects) were spaced along the length of the fibre. These configurations were found to allow significantly different behaviours. For example, the light-ion interactions could be tuned to become very much stronger or very much weaker than for the single-ion case.