Christophe Galland

Optomechanics refers to the study of coherent interaction between light and mechanical oscillators and the associated backaction forces. It offers a path toward fundamental tests of quantum mechanics on massive objects and their use in quantum technologies, e.g., as transducers, frequency converters and memories.

Molecules support internal vibrations that may be seen as the ultimate nanomechanical oscillators in terms of low effective mass and high resonance frequencies (typically >10 THz) [1]. At the crossroads of surface science, molecular spectroscopy, quantum optics and cavity optomechanics, molecular optomechanics offers a new paradigm for the study of quantum coherence among vibrating molecular bonds and their use in nanoscale devices.

In this seminar, I will first rapidly summarize recent experiments that utilize quantum backaction inherent to vibrational Raman scattering as a way to generate and probe macroscopic quantum coherence and entanglement between collective molecular vibrations and optical photons [2-5]. Next, I will show how molecular oscillators coupled to dual-band plasmonic nanocavities can be leveraged for coherent frequency conversion between mid-infrared and visible light [6,7].

Taken together, these results demonstrate that molecular oscillators may have a role to play in quantum and nano-technologies; conversely, concepts borrowed from quantum optics may help to better understand well-established experimental methods such as surface-enhanced Raman scattering, provided that we can also better control of plasmonic structures behave under laser illumination [8,9].

[1] P. Roelli, Nature Nano 11, 164-169 (2016)

[2] M. Anderson, Physical Review Letters 120, 233601 (2018)

[3] S. Tarrago Velez, Physical Review X 9, 041007 (2019)

[4] S. Tarrago Velez, https://arxiv.org/abs/2105.00213

[5] S. Tarrago Velez, Science Adv. eabb0260 (2020)

[6] P. Roelli, Physical Review X 10 (3), 031057

[7] W. Chen, Science 374, 1264-1267 (2021)

[8] A. Ahmed, ACS Photonics 8, 1863–1872 (2021)

[9] W. Chen, Nature Comm. 12, 2731 (2021)