Non-reciprocal energy transfer through the Casimir effect.

One of the fundamental predictions of quantum mechanics is the occurrence of random fluctuations in a vacuum caused by the zero-point energy. Remarkably, quantum electromagnetic fluctuations can induce a measurable force between neutral objects, known as the Casimir effect, and it has been studied both theoretically and experimentally. The Casimir effect can dominate the interaction between microstructures at small separations and is essential for micro- and nanotechnologies.

Ultrasensitive torque detection with an optically levitated nanorotor.

Torque sensors such as the torsion balance enabled the first determination of the gravitational constant by Henri Cavendish and the discovery of Coulomb's law. Torque sensors are also widely used in studying small-scale magnetism, the Casimir effect and other applications. Great effort has been made to improve the torque detection sensitivity by nanofabrication and cryogenic cooling.

Optically Levitated Nanodumbbell Torsion Balance and GHz Nanomechanical Rotor.

Levitated optomechanics has great potential in precision measurements, thermodynamics, macroscopic quantum mechanics, and quantum sensing. Here we synthesize and optically levitate silica nanodumbbells in high vacuum. With a linearly polarized laser, we observe the torsional vibration of an optically levitated nanodumbbell.

Stable emission and fast optical modulation of quantum emitters in boron nitride nanotubes.

Atom-like defects in two-dimensional (2D) hexagonal boron nitride (hBN) have recently emerged as a promising platform for quantum information science. Here, we investigate single-photon emissions from atomic defects in boron nitride nanotubes (BNNTs). We demonstrate the first, to the best of our knowledge, optical modulation of the quantum emission from BNNTs with a near-infrared laser.

Experimental Test of the Differential Fluctuation Theorem and a Generalized Jarzynski Equality for Arbitrary Initial States.

Nonequilibrium processes of small systems such as molecular machines are ubiquitous in biology, chemistry, and physics but are often challenging to comprehend. In the past two decades, several exact thermodynamic relations of nonequilibrium processes, collectively known as fluctuation theorems, have been discovered and provided critical insights. These fluctuation theorems are generalizations of the second law and can be unified by a differential fluctuation theorem.

Torsional Optomechanics of a Levitated Nonspherical Nanoparticle.

An optically levitated nanoparticle in vacuum is a paradigm optomechanical system for sensing and studying macroscopic quantum mechanics. While its center-of-mass motion has been investigated intensively, its torsional vibration has only been studied theoretically in limited cases. Here we report the first experimental observation of the torsional vibration of an optically levitated nonspherical nanoparticle in vacuum.

Electron spin control of optically levitated nanodiamonds in vacuum.

Electron spins of diamond nitrogen-vacancy (NV) centres are important quantum resources for nanoscale sensing and quantum information. Combining NV spins with levitated optomechanical resonators will provide a hybrid quantum system for novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centres in low vacuum.

Assembly and densification of nanowire arrays via shrinkage.

Chemically synthesized semiconductor nanowires (NWs) have demonstrated substantial promise for nanoelectronics, nanoenergy, and nanobiotechnology, but the lack of an effective and controllable assembly process has limited the wide adoption of NWs in these areas. Here we demonstrate a facile, robust, and controllable approach to assembling and densifying a parallel array of NWs using shrinkable shape memory polymers. Using thermal-induced shrinkage of polystyrene, we were able to successfully assemble and densify NW arrays up to close-packing and, furthermore, achieve tunable density (up to ∼300% amplification of density) by controlling the shrinkage process.