Understanding and controlling light-matter interactions is a cornerstone of physics and an essential
resource for quantum technologies, communication and metrology. Levitated nano-objects offer a
new paradigm to study the interaction between electromagnetic fields and matter at the very
interface between quantum optics and macroscopic electrodynamics [1]. What is intriguing about
levitated objects in high vacuum is that they can interact with the outside world only via their
coupling to the electromagnetic field. This both grants an exceptional isolation from the
environment, while optical fields can be used to precisely interrogate and manipulate the system.
So far, research on levitated nano-objects has mainly focused on controlling the center-of-mass
motion and rotational degrees of freedom [2,3]. However, nanoparticles possess also highly
discretised vibrational modes in the GHz band [4]: such internal degrees of freedom, remain
scarcely explored.
In this seminar, I will introduce the levitodynamics toolbox and discuss two experiments. The first,
is about the optimal measurement of the center of mass position of a levitated nanoparticle. I will
show how the position measurement outcomes, in conjunction with a feedback scheme, can be
used to prepare the motional groundstate of the levitated object. The second, is about probing the
vibrational modes of levitated nanoparticles. I will discuss how these vibrations couple to the
electromagnetic field, how to detect their optical signatures using a two-tone spectroscopy and
show some preliminary results.
[1] C. Gonzalez-Ballestero et al. Science 374, 6564 (2021)
[2] L. Magrini et al. Nature 595, 373-377 (2021) - F. Tebbenjohanns et al. Nature 595, 378–382 (2021)
[3] F. van der Laan et al. PRL 127, 123605 (2021)
[4] M.H. Kuok et al. PRL 90, 255502 (2003)
