Nanospheres

In this project, we are studying the interaction between optical fields and the mechanical motion of a levitated nano-object. Our aim is to prepare and study non-Gaussian quantum states of motion (ie, with negative values ​​in the Wigner function).

A cavity-mediated interaction provides a link between the quantum and the macroscopic worlds.

Ion-assisted levitated quantum optomechanics

Typically, it is used in an optical field, eg, using optical tweezers or a quadrupole trap, in which the object oscillates periodically around its equilibrium position. The motion of the object is then placed in the field of an optical cavity. This dispersive coupling makes it possible to implement optomechanical protocols such as motional readout, resolved sideband cooling, and - once the object has been cooled to the motional ground state - entanglement with the cavity field.

Both a nanosphere and an ion are coupled to an optical cavity.

 Despite its similarity to the field of cavity QED, cavity optomechanics does not require the presence of an electronic transition. Therefore, mesoscopic oscillators can in principle be used to prepare mechanical quantum states such as center-of-mass superpositions. HOWEVER, coupling a levitated nanosphere to a macroscopic Fabry-Perot resonator leads to very small single-photon opto mechanical coupling rates g  0  Which, for realistic parameters, are smaller than the cavity photon lifetime κ -1 . Thus, the optomechanical system typically operates in the so-called linearized regime, in which the mechanical oscillator's steady state is characterized by a positive Wigner function.

To overcome these limitations, we follow a new approach to the field of levitated optomechanics to multiple objects, more specifically, to a single ion and a silica nanosphere. Both species will be described as using on-chip linear quadrupole trap driven by two frequencies, with the cavity field aligned along the trap axis. 400 microns on up, making our levitation scheme compatible with a range of cavities lengths up to 300 microns.

This configuration will allow a hybrid system where both the internal levels of energy and the levitated nanosphere's center-of-mass motion couple to the cavity field. Outside the resolved sideband regime and the preparation of non-classical motional states of the nanosphere. Additionally, our system aims to allow multiple modes of molecular dynamics with multiple levitated nanoparticles.

Project Members

Dmitry Bykov, Lorenzo Dania, 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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