Engineering collective light-matter interactions



Strong light-matter coupling---without cavities---requires a high optical depth such that any incident photon has a high probability of interacting. For a single dipole, optical depth (extinction) optimization  is achieved by frequency matching and spatial mode matching of the incident light. [1] For many dipoles, optical depth maximisation becomes a complex many-body problem, where one may need to include the effects of the interactions between dipoles and the vector nature of the electromagnetic field.


In general, for many dipoles, the light interacts with a collective mode, and one can exploit interactions to engineer the collective response as in Rydberg EIT [2] or using sub-wavelength arrays [3]. In this talk I will review the opportunities and challenges of such collective mode engineering.


References

[1] C. S. Adams and I. G. Hughes, {\it Optics f2f}, OUP (2019). 


[2] O. Firstenberg, C. S. Adams and S. Hofferberth, J. Phys. B {\bf 49}, 152003 (2016). 


[3] R. J. Bettles, S. A. Gardiner, and C. S. Adams, Phys. Rev. Lett. {\bf 116}, 103602 (2016).