Research

Random quantum vacuum fluctuations exist everywhere, and it leads to the Casimir interaction between macroscopic bodies. We proposed and realized the first Casimir diode system to regulate energy transfer by quantum fluctuations. We achieved the precision measurement of Casimir force by a home-built dual-cantilever system. Non-reciprocity is realized by dynamical modulation near the exceptional point. This is the first observation of non-reciprocal energy transfer by Casimir force, and it shows more perspectives and opportunities of utilizing quantum fluctuations. This work is recently accepted by Nature Nanotechnology. Theoretically, I have proposed to detect the long-sought Casimir torque and vacuum friction by optomechanical system. These two theoretical works were published in Physical Review A and Nanophotonics.

The levitated particle in the optical tweezer can have an ultrahigh quality factor due to the excellent isolation from the thermal environment. We have realized the levitated Cavendish torsion balance system with a nanodumbbell in a linearly polarized optical tweezer. We also observed the GHz nanomechanical rotor with a levitated nanodumbbell in a circularly polarized optical tweezer. We utilized the ultrafast rotation to achieve an unprecedented torque sensitivity of 4e-27 Nm/sqrt(Hz). These two experimental works were published in Physical Review Letters and Nature Nanotechnology and selected as one of the APS top 10 “Highlights of the Year” of 2018.

Theoretically, we have proposed schemes to realize quantum information processing and scalable quantum network with closely spaced diamond color centers. A gradient strain field and a gradient magnetic field are applied to the system to split each optical transition frequency and electron spin resonance frequency for spin control and readout. Experimentally, we have observed plasmonic-enhanced quantum emissions from ion-implanted hexagonal boron nitride (hBN) nanosheets. We have also observed single-photon emissions from one-dimensional boron nitride nanotubes (BNNTs). These three works were published in Optical Materials Express, Nano Letters, and Optics Letters.