Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum control of a nanoparticle optically levitated in cryogenic free
  space   Tests of quantum mechanics on a macroscopic scale require extreme control
over mechanical motion and its decoherence. Quantum control of mechanical
motion has been achieved by engineering the radiation-pressure coupling between
a micromechanical oscillator and the electromagnetic field in a resonator.
Furthermore, measurement-based feedback control relying on cavity-enhanced
detection schemes has been used to cool micromechanical oscillators to their
quantum ground states. In contrast to mechanically tethered systems, optically
levitated nanoparticles are particularly promising candidates for matter-wave
experiments with massive objects, since their trapping potential is fully
controllable. In this work, we optically levitate a femto-gram dielectric
particle in cryogenic free space, which suppresses thermal effects sufficiently
to make the measurement backaction the dominant decoherence mechanism. With an
efficient quantum measurement, we exert quantum control over the dynamics of
the particle. We cool its center-of-mass motion by measurement-based feedback
to an average occupancy of 0.65 motional quanta, corresponding to a state
purity of 43%. The absence of an optical resonator and its bandwidth
limitations holds promise to transfer the full quantum control available for
electromagnetic fields to a mechanical system. Together with the fact that the
optical trapping potential is highly controllable, our experimental platform
offers a route to investigating quantum mechanics at macroscopic scales.

26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an