Chip-scale molecule trapping by a blue-detuned metasurface hollow beam

Abstract

We propose a tightly focused hollow beam to trap cold molecules by using a metasurface grating, which has a hybrid phase with focusing and completely destructive interference functions. The intensity distributions of the hollow beam in free space concerning different structural parameters of the grating are theoretically studied in detail. The influences of both the discrete and continuous phases of the grating on the intensity distribution of the modulated optical field are compared. Our theoretical study shows that such a blue-detuned beam can provide a deep potential to trap cold molecules with a low photon scattering rate and a long trap lifetime. Our studies suggest that the metasurface-based optical chip is applicable to trap molecules and can be an ideal platform for building a robust quantum laboratory.

Generation of a blue-detuned optical storage ring by a metasurface and its application in optical trapping of cold molecules

“…Since a phase-transmitting-type metasurface is nearly two-dimensional and the thickness d is generally kept unchanged in the manufacturing process, the phase accumulation φ is realized by changing the effective refractive index n eff at different positions. [20,22] Change in n eff is generally achieved by constructing a material microstructure of a higher refractive index on a substrate of a lower refractive index.…”

“…In contrast, an all-optical storage ring of cold molecules does not require the molecule to possess a permanent electric or magnetic dipole moment but induces an electric dipole moment to generate gradient forces to confine molecules into a potential trap. [20,22] Moreover, it is naturally immune to Majorana-type spin flips, which lead to the loss of trapped molecules. Therefore, the optical storage ring could have a broader range of applications.…”

“…In this case, molecules will be trapped or guided in a blue-detuned hollow beam. [22,23] A hollow beam storage ring based on this effect has unique advantages: the deep potential enables trapping of molecular wave packets whose average velocity is not zero; the low photon scattering rate and long trap lifetime enables the interaction of molecules with other molecules or electromagnetic fields many times at the specific location and time. Such features of the storage ring provide an effective way to study high-resolution molecular spectroscopy, ultra-cold collisions and reactions.…”

Flexible Generation and Manipulation of Microwave Bottle Beam Using a Reconfigurable Metamirror

“…Due to such exotic property, many efforts have been devoted to bottle beams in optics and acoustic regimes, which serve as optical tweezers [1] and optical trappers. [2,3] A variety of methods has been proposed to implement bottle beam generation. A primary way is to exploit the destructive interference between two beams with different parameters so as to produce a circular dark region at the mutual focus of the two beams.…”

Efficient generation of optical bottle beams

“…Another approach uses a single optical beam with a functional optical component, such as a diffractive optical element [9], hologram [2], or spatial light modulator [10], [11]. Recently, metasurfaces have also been considered for bottle-beam generation [12]- [14]. Due to the compact size of metasurfaces, this approach has potential for chip-scale optical trapping.…”