Creative research takes time

Nowadays funding agencies prioritise research with immediate applications. Grants for early career researchers provide funding for only a few years, requiring funded projects to have a quick and clear path to fruition. However, in basic research the eventual applications are often not those that were first envisaged.

Perhaps my favourite research project was our study of topological effects in "leaky" optical systems, published earlier this year in Nature Physics. See here for a popular summary. I am proud of this work not merely because the results were eventually published in a glossy journal, but rather because it was a pure, curiosity-driven project involving short bursts of inspiration and progress separated by many months.

This project originated from a grant application we prepared in August 2018. The host institution had expertise in photonic crystal fibers, so we were interested in whether the photonic crystal fiber platform could be used to observe interesting topological phenomena. However, photonic crystal fibers are leaky wave systems which continuously radiate energy into their environment, so it was not clear whether our experience in designing topological states for bound modes would be useful in this setting.

We started working on the idea by implementing well-known approaches for numerically computing leaky modes with the help of a tutorial article, studying some simple one-dimensional examples to gain some intuition for the platform. 

By April 2019 we had developed a tight binding-like formalism allowing us to design and study topological wave effects in leaky wave systems, but we did not know what our formalism could be useful for apart from computing the decay rates of leaky topological edge states. 

After a few conferences and many discussions with other researchers, in October 2019 we finally stumbled upon the neat idea of using radiation losses to controllably fill energy bands and measure their bulk topological invariants. 

We finished a draft manuscript by the end of November 2019 and shared with some collaborators. Their feedback was that the idea was interesting, but it wasn't clear how easy it would be to experimentally test our theory. 

We spent a few more months carrying out numerical simulations of possible designs and polishing the manuscript, finally submitting it in May 2020. Our collaborators' impression was echoed by the referees, who requested more detailed and explicit simulations of our designs in a revised manuscript, which was finally accepted in December 2020.

Take home messages:

-Find inspiration for new lines of research in old reviews and tutorials, not the latest papers published in high impact journals.

-If you get stuck don't be afraid to put the project aside for a few months and work on other directions.

-Creative research takes time - 2.5 years between the initial idea and eventual publication in this case (a theory project). Experimental projects can take even longer.