Related papers: Short-range force detection using optically-cooled…
It is known that probing gravity in the submillimeter-micrometer range is difficult due to the relative weakness of the gravitational force. We intend to overcome this challenge by using extreme temporal precision to monitor transient…
We describe the use of optically levitated microspheres as test masses in experiments aimed at reaching and potentially exceeding the standard quantum limit for position measurements. Optically levitated microspheres have low mass and are…
Cooling down nanomechanical force probes is a generic strategy to enhance their sensitivities through the concomitant reduction of their thermal noise and mechanical damping rates. However, heat conduction mechanisms become less efficient…
We propose a sensing scheme for detecting weak forces that achieves Heisenberg-limited sensitivity without relying on entanglement or other non-classical resources. Our scheme utilizes coherent averaging across a chain of N optomechanical…
We report an $\textit{in situ}$ mass measurement of approximately-$4.7{\text -}\mu$m-diameter, optically levitated microspheres with an electrostatic co-levitation technique. The mass of a trapped, charged microsphere is measured by holding…
Torque sensors such as the torsion balance enabled the first determination of the gravitational constant by Cavendish and the discovery of Coulomb's law. Torque sensors are also widely used in studying small-scale magnetism, the Casimir…
Interferometric position detection of levitated particles is crucial for the centre-of-mass (CM) motion cooling and manipulation of levitated particles. In combination with balanced detection and feedback cooling, this system has provided…
Significant effort has been devoted to searching for new fundamental forces of nature. At short length scales (below approximately 10 nm), the strongest experimental constraints come from neutron scattering from individual nuclei in gases.…
We describe the design and construction of a new apparatus for detecting or constraining deviations from Newtonian gravity at short length scales. The apparatus consists of a new type of probe with rotary mass actuation and cantilever-based…
Methods for controlling the motion of single particles, optically levitated in vacuum, have developed rapidly in recent years. The technique of cold damping makes use of feedback-controlled, electrostatic forces to increase dissipation…
We report on the injection locking of an optically levitated nanomechanical oscillator (a silica nanosphere) to resonant intensity modulations of an external optical signal. We explore the characteristic features of injection locking in…
We demonstrate photophoretic force-based optical trapping of multiple absorbing particles in air by loosely focusing a Gaussian beam with a series of convex lenses of different focal lengths, and investigate the dependence of the number of…
We propose to use optical tweezers to probe the Casimir interaction between microspheres inside a liquid medium for geometric aspect ratios far beyond the validity of the widely employed proximity force approximation. This setup has the…
The optomechanical force sensor in non-Markovian environment for a mechanical oscillator is presented. By performing homodyne detection we obtain an generally expression for the output signal. It is shown that the weak force detection is…
We report an experimental test of non-Newtonian gravitational forces at mi- crometer range. To experimentally subtract off the Casimir force and the electrostatic force background, differential force measurements were performed by sensing…
The symmetron, one of the light scalar fields introduced by dark energy theories, is thought to modify the gravitational force when it couples to matter. However, detecting the symmetron field is challenging due to its screening behavior in…
We propose a new method to detect short-range \textit{P-} and \textit{T-} violating interactions between nucleons, based on measuring the precession frequency shift of polarized $^3$He nuclei in the presence of an unpolarized mass. To…
We report a weighing metrology experiment of a single silica microsphere optically trapped and immersed in air. Based on fluctuations about thermal equilibrium, three different mass measurements are investigated, each arising from one of…
All physical interactions are mediated by forces. Ultra-sensitive force measurements are therefore a crucial tool for investigating the fundamental physics of magnetic, atomic, quantum, and surface phenomena. Laser cooled trapped atomic…
The use of levitated nanospheres represents a new paradigm for the optomechanical cooling of a small mechanical oscillator, with the prospect of realising quantum oscillators with unprecedentedly high quality factors. We investigate the…