Light-matter interactions on nanoscale – exploring optics with electrons

Who: N. Asger Mortensen
When: Wednesday, October 4, 2017 at 12:15-13:15
Where: Danish IAS conference room

With the maturing of nanofabrication technologies, light-matter interactions can now be explored in artificially tailored metallic nanostructures that support plasmons, i.e. collective oscillations of the electron gas. Quite fascinatingly, electromagnetic fields can be manipulated beyond the diffraction limit of light, paving the way for studies of light-matter interactions at the interface between classical electrodynamics and the nano world intuitively influenced by quantum physics. In our effort to understand plasmons and explore optical properties of matter, we are traditionally equipped with optical techniques and probes. However, the optical diffraction limit represents a fundamental obstacle to obtain near-field information on plasmons confined to the true nanoscale. Naturally, we cannot bend the laws of physics, but we may cope with the diffraction limit by turning from light fields to other waves of shorter wavelength. The perhaps paradoxical choice is to substitute beams of photons with ultra-fast electrons, i.e. exploring optical properties of plasmons with electrons rather than light. I will give examples how state-of-the-art electron microscopes opens access to detailed explorations of light-matter interactions down to the atomic scale [1,2], thereby also giving us a glimpse into the possibilities for use of extreme plasmonics for emerging quantum technologies [3], such as the ultimate control of light-emission dynamics of single quantum emitters [4].

[1] S. Raza, N. Stenger, A. Pors, T. Holmgaard, S. Kadkhodazadeh, J.B. Wagner, K. Pedersen, M. Wubs, S.I. Bozhevolnyi, and N.A. Mortensen, ”Extremely confined gap surface plasmon modes excited by electrons”, Nature Communications 8, 4125 (2014).

[2] S. Raza, S. Kadkhodazadeh, T. Christensen, M. Di Vece, M. Wubs, N.A. Mortensen, and N. Stenger, ”Multipole plasmons and their disappearance in few-nanometre silver nanoparticles”,
Nature Communications 6, 8788 (2015).
[3] S.I. Bozhevolnyi and N.A. Mortensen, “Plasmonics for emerging quantum technologies”, Nanophotonics 6, 1185 (2017).
[4] S.I. Bozhevolnyi and J.B. Khurgin, ”The case for quantum plasmonics”, Nature Photonics 11, 398 (2017).