Optomechanics studies the interaction of light with moving objects, an essential resource for sensing, metrology, and the investigation of fundamental aspects of quantum mechanics with mesoscopic systems. To harness coherent optomechanical interactions, it is crucial to shield the low-energy excitations of the system from decoherence, which may arise, for instance, due to uncontrolled mechanical energy loss into the environment. In this sense, levitated objects in ultra-high vacuum offer a new paradigm [1]. By eliminating clamping losses and the background gas, an exceptional degree of isolation from the environment can be achieved, while optical fields can be used to precisely interrogate and manipulate the system. This has recently enabled the measurement-based motional groundstate cooling of a levitated object [2,3]. Moreover, levitodynamics has been proposed as a playground to develop force transducers with unparalleled sensitivity, or to perform matter-wave interferometry with mesoscopic objects in a hitherto inaccessible parameter regime, possibly allowing to test collapse models [4] and the interplay between quantum mechanics and gravity [5].
In this seminar, I will introduce the levitodynamics toolbox and discuss two experiments. In the first, I will show how we achieve quantum control over the center-of-mass degrees of freedom of a levitated nanoparticle, thereby preparing the motional ground state of the levitated object. In the second, I will show the results of some preliminary experiments where we apply rapid optical pulse sequences to manipulate the mechanical state. The pulse sequences can be employed both for sensing stray electric fields, as well as for generating a squeezed motional state. Finally, I will discuss the implications and challenges highlighted by these results towards the goal of delocalizing the wavefunction of such a mesoscopic object over a length scale comparable to the object itself.
[1] C. Gonzalez-Ballestero et al. - Science 374, 6564 (2021).
[2] L. Magrini et al. - Nature 595, 373-377 (2021)
[3] F. Tebbenjohanns et al. Nature 595, 378–382 (2021).
[4] O. Romero-Isart - PRA 84, 052121 (2011)
[5] M. Aspelmeyer - arXiv:2203.05587 (2022).
Prof. Marco Bazzan
