Dr. Tomáš Neuman
IPCMS – Département Surfaces et Interfaces , CNRS, Strasbourg, France
"From plasmon-mediated molecular spectroscopy to electro-optics and quantum technologies"
Vibrational, electronic, and spin excitations in molecules can identify molecules in spectroscopy, but also play a role in molecular chemical reactivity, or find technological applications e.g. in superresolution microscopy or infrared-to-optical transduction [1]. Recently, excitations in single molecules and molecular networks have been proposed to serve as physical platforms for qubits or for nanoscale sources of non-classical photon states [2]. To fully take advantage of the molecular platforms it is, therefore, necessary to elucidate how molecular excitations can be detected, engineered, and controlled, especially on the single- or a few-molecular scale.
I will discuss how nanoscale metallic structures supporting collective electronic excitations - plasmons - can be used to enhance the interaction between photons and molecular excitations and thus detect and control them, and even to break well-established spectroscopic selection rules [3]. Full understanding of the plasmon-mediated light-matter interactions also enables novel spectroscopic methods exploiting the correlated information about transport and optical properties of molecules. A particular example of electroluminescence spectroscopy in a scanning tunneling microscope used to elucidate the tautomerization dynamics in free-base phthalocyanine molecules will be discussed [4].
Finally, I will elaborate on the potential of molecules or molecule-like solid-state defects for quantum technologies exploiting their optical activity, strain susceptibility, and spin properties. In particular, the potential of molecular spins to serve as optically, mechanically, and magnetically controllable qubits [5], or the possibilities to manipulate spin-forbidden molecular transitions will be discussed.
[1] P. Roelli, D. Martin-Cano, T.J. Kippenberg, C. Galland, Physical Review X 10 (3), 031057 (2020).
[2] M.R. Wasielewski, M.D.E. Forbes, N.L. Frank, et al., Nature Reviews Chemistry, 1-15 (2020).
[3] T. Neuman, R. Esteban, D. Casanova, F.J. García-Vidal, J. Aizpurua, Nano Letters 18 (4), 2358-2364 (2018).
[4] B. Doppagne, T. Neuman, R. Soria-Martinez, et al., Nature Nanotechnology 15 (3), 207-211 (2020).
[5] T. Neuman, D. Wang, P. Narang, Physical Review Letters 125 (24), 247702 (2020).