Ashleysetter/Optosim: Initial Release

This is the initial release of this package. The package has been restructured such that the organisation is tidier and more easy to extend. The current simulation supports the modelling of free dynamics plus x^4 non-linearity in the form of the harmonic potential, pulsed squeezing, and driving and cooling on resonance and at double the frequency.</span

Dataset for: Characterization of Non-linearities through Mechanical Squashing in Levitated Optomechanic

Data supporting the article: &#39;Characterization of Non-linearities through Mechanical Squashing in Levitated Optomechanics&#39; </span

Data used in article: Real-Time Kalman filter: Cooling of an Optically Levitated Nanoparticle

Data associated and used in the following article: &#39;Real-Time Kalman filter: Cooling of an Optically Levitated Nanoparticle&#39; which is published in Physical Review A with DOI: 10.1103/PhysRevA.97.033822</span

Data for: Chapter 4 of Cooling of a Mesoscopic Single-Particle Harmonic Oscillator using Real-time Digital Control Systems

The data used in chapter 4 of Ashley Setter&#39;s PhD thesis: Cooling of a Mesoscopic Single-Particle Harmonic Oscillator using Real-time Digital Control Systems.</span

Data used in article: Precession Motion in Levitated Optomechanics

Data associated and used in the following article: Ulbricht, H., Toros, M., Rashid, M., &amp; Setter, A. J. (2018). Precession motion in levitated optomechanics. Physical Review Letters, 121(25), [253601]. DOI: 10.1103/PhysRevLett.121.253601</span

Precession motion in levitated optomechanics

We investigate experimentally the dynamics of a non-spherical levitated nanoparticle in vacuum. In addition to translation and rotation motion, we observe the light torque-induced precession and nutation of the trapped particle. We provide a theoretical model, which we numerically simulate and from which we derive approximate expressions for the motional frequencies. Both, the simulation and approximate expressions, we find in good agreement with experiments. We measure a torque of 1.9±0.5�10�23 Nm at 1�10�1 mbar, with an estimated torque sensitivity of 3.6±1.1�10�31 Nm/�Hz at 1�10�7 mbar

Ultralow mechanical damping with Meissner-levitated ferromagnetic microparticles

Levitated nanoparticles and microparticles are excellent candidates for the realization of extremely isolated mechanical systems, with a huge potential impact in sensing applications and in quantum physics. Magnetic levitation based on static fields is a particularly interesting approach, due to the unique property of being completely passive and compatible with low temperatures. Here, we show experimentally that micromagnets levitated above type-I superconductors feature very low damping at low frequency and low temperature. In our experiment, we detect 5 out of 6 rigid-body mechanical modes of a levitated ferromagnetic microsphere, using a dc SQUID (Superconducting Quantum Interference Device) with a single pick-up coil. The measured frequencies are in agreement with a finite element simulation based on ideal Meissner effect. For two specific modes we find further substantial agreement with analytical predictions based on the image method. We measure damping times τ exceeding 104 s and quality factors Q beyond 107, improving by 2−3 orders of magnitude over previous experiments based on the same principle. We investigate the possible residual loss mechanisms besides gas collisions, and argue that much longer damping time can be achieved with further effort and optimization. Our results open the way towards the development of ultrasensitive magnetomechanical sensors with potential applications to magnetometry and gravimetry, as well as to fundamental and quantum physics

Dynamical model selection near the quantum-classical boundary

We discuss a general method of model selection from experimentally recorded time-trace data. This method can be used to distinguish between quantum and classical dynamical models. It can be used in postselection as well as for real-time analysis, and offers an alternative to statistical tests based on state-reconstruction methods. We examine the conditions that optimize quantum hypothesis testing, maximizing one's ability to discriminate between classical and quantum models. We set upper limits on the temperature and lower limits on the measurement efficiencies required to explore these differences, using an experiment in levitated optomechanical systems as an example