State Expansion of a Levitated Nanoparticle in a Dark Harmonic Potential.

We spatially expand and subsequently contract the motional thermal state of a levitated nanoparticle using a hybrid trapping scheme. The particle's center-of-mass motion is initialized in a thermal state (temperature 155 mK) in an optical trap and then expanded by subsequent evolution in a much softer Paul trap in the absence of optical fields. We demonstrate expansion of the motional state's standard deviation in position by a factor of 24. In our system, state expansion occurs devoid of backaction from photon recoil, making this approach suitable for coherent wave function expansion.

Ultrahigh Quality Factor of a Levitated Nanomechanical Oscillator.

A levitated nanomechanical oscillator under ultrahigh vacuum is highly isolated from its environment. It has been predicted that this isolation leads to very low mechanical dissipation rates. However, a gap persists between predictions and experimental data. Here, we levitate a silica nanoparticle in a linear Paul trap at room temperature, at pressures as low as 7×10^{-11} mbar. We measure a dissipation rate of 2π×69(22) nHz, corresponding to a quality factor exceeding 10^{10}, more than 2 orders of magnitude higher than previously shown. A study of the pressure dependence of the particle's damping and heating rates provides insight into the relevant dissipation mechanisms.

Hybrid electro-optical trap for experiments with levitated particles in vacuum.

We confine a microparticle in a hybrid potential created by a Paul trap and a dual-beam optical trap. We transfer the particle between the Paul trap and the optical trap at different pressures and study the influence of feedback cooling on the transfer process. This technique provides a path for experiments with optically levitated particles in ultra-high vacuum and in potentials with complex structures.

Position Measurement of a Levitated Nanoparticle via Interference with Its Mirror Image.

Interferometric methods for detecting the motion of a levitated nanoparticle provide a route to the quantum ground state, but such methods are currently limited by mode mismatch between the reference beam and the dipolar field scattered by the particle. Here we demonstrate a self-interference method to detect the particle's motion that solves this problem. A Paul trap confines a charged dielectric nanoparticle in high vacuum, and a mirror retro-reflects the scattered light. We measure the particle's motion with a sensitivity of 1.7×10^{-12} m/sqrt[Hz], corresponding to a detection efficiency of 2.1%, with a numerical aperture of 0.18. As an application of this method, we cool the particle, via feedback, to temperatures below those achieved in the same setup using a standard position measurement.