Nanospheres

In our experiments we study interaction between single atomic ions and quantized motion of levitated silica nanospheres. Our goal is to prepare non-Gaussian quantum state of motion of a macroscopic object.

Our project addresses the following questions:

  • What happens to a levitated nanosphere when it is placed in ultra-high-vacuum?
  • How can we co-trap a nanosphere and a single calcium ion?
  • How can we use nanospheres and ions in an optical cavity to prepare non-Gaussian states of motion?

Ion assisted optomechanics

nanospheres

We are currently building and experiment to study interaction between atomic quantum system, which in our case is a trapped 40Ca+ ion, and an optomechanical element represented by a levitated nanoparticle. In the core of the experiment is an on chip linear Paul trap with high optical access and an optical cavity. The former will be used to trap atomic ions and nanoparticles the latter will mediate coupling between internal structure of the ion and the motion of the levitated nanoparticle.

Ion-nanosphere co-trapping

In order to build a hybrid optomechanical system one needs to trap simultaneously a single 40Ca+ ion and a single nanosphere.

co-trapping

One approach is to trap both objects in the same Paul trap using a two-tone drive of the Paul trap: slow field (~kHz) for trapping nanospheres, and fast field (~MHz) for trapping ions. The two-tone drive is necessary due to large charge-to-mass ratio mismatch between the atomic ion and the nanoparticle. An alternative approach would be to use the Paul trap to trap the ion and an optical trap to trap the nanoparticle. To reduce the influence of the particle motion on the position of the ion we can damp the oscillations of the nanosphere down to mK effective temperature by means of feedback cooling [1]. The experiment is carried out at pressures lower than 1e-10 mbar, a condition which makes ion trapping possible.

Trapping particles in ultra-high vacuum

Working with single atomic ions requires an ultra-high vacuum (UHV) compatible setup. Our experiments with levitated nanoparticles in Paul traps benefit from a clean trap loading procedure. The loading technique we use is based on laser-induced acoustic desorption (LIAD) of nanoparticles from a metallic foil, and temporal control of the trapping potential.

delayed

With this method we demonstrated direct loading of single nanoparticles in Paul traps at pressure of 10-7 mbar [2], and more recently down to pressures lower than 10-10 mbar. Levitation in UHV opens door to study particle’s motional dynamics in low decoherence regimes.

[1] L. Dania, D. S. Bykov, M. Knoll, P. Mestres, and T. E. Northup, Phys. Rev. Research 3 (2021)

[2]  D. S. Bykov, P. Mestres, L. Dania, L. Schmöger, and T. E. Northup, Appl. Phys. Lett. 115 (2019)

Project Members 

Dmitry Bykov, Lorenzo Dania, Florian Goschin, Katharina Heidegger, Max Meusburger, Tracy Northup

Former members: Matthias Knoll, Pau Mestres, Lisa Schmöger

Funding

Funding for this project is provided by

FWF The Austrian Science Fund through the START Program (Project Y 951).



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