Optical Ring Lattices Research Articles

Generation of stable ultraviolet optical ring lattices using monolithic AlN metasurfaces for cooling atoms

Optical ring lattices containing multiple optical traps in a ring configuration have gradually evolved into indispensable tools in cold atom experiments. However, the conventional methods for generating optical ring lattices require bulky apparatus and work at a limited wavelength range. Recently, metasurfaces have emerged as promising ultra-compact platforms for the implementation of optical ring lattices. Here, we report the generation of ultraviolet optical ring lattices using monolithic AlN metasurfaces. The feasibility of trapping atom and atom-like systems in the optical ring lattices is validated through theoretical calculation of the optical forces using the dipole model. The adoption of AlN metasurfaces can reduce the size and cost of generating optical ring lattices and thus give rise to diverse applications such as transportable atom clocks.

Manipulations of cold atoms in a one-dimensional ring lattice

The dynamics of Bose–Einstein condensates in a one-dimensional ring optical lattice is related to the interplay of the open system conditions and the initial atomic distribution. The circulation evaluation model based on the relative atomic density on each site is established to analyze the circulation strength under low dissipation. The direction of the circulation due to the symmetry breaking can be manipulated by changing the primary atomic distribution and the number of lattice sites. The effect of the atomic interaction on the atom flow in the optical ring lattice is analyzed to maintain the current interval rotation behavior.

Harnessing Laguerre-Gaussian Beams to Construct Quasi-Nondiffracting Optical Ring Lattices

We construct a family of optical ring lattices that manifest the quasi-nondiffracting property via superposition of high-radial-order Laguerre-Gaussian beams. A theoretical derivation of the optical ring lattice along with the validity condition is presented, and its evolution behaviors are investigated in comparison with the diffraction-free Bessel beams. Moreover, multiple ultralong bright channels or optical tubes with various transverse profiles can be formed with the ring optical lattices. As a proof of concept, flexible generation of the lattice beams was demonstrated by complex wavefront engineering using a binary digital micromirror device. We anticipate that the quasi-nondiffracting ring lattices and the ultralong optical channels might motivate novel applications in optical trapping and high-resolution microscopy.

Azimuthal phase-shifted zone plates to produce petal-like beams and ring lattice structures

We aim here to present two models of spiral zone plate-based diffractive elements. To this end, it is shown that by a given combination of two spiral zone plates (SZPs) with opposite-signed charge strengths some novel elements are born whose phase structures are azimuthally shifted. Therefore, they are named azimuthal phase-shifted zone plates. Generally speaking, it is illustrated that both of the two models have the same diffractive functions in generating a variety of petal-like and optical ring lattice beams. Regarding the topological charge of the superimposed SZPs denoted by P1 and P2, it is also elaborated that when the modulus of |P1|−|P2| is of unity, the former beam is generated, while the values greater than unity cause the latter one to be generated. Additionally, the number of petals or lattices is simply manageable and given by |P1|+|P2|. Furthermore, defocusing surveys manifest preserving the shape of the beams in a rather long focal depth and partial rotation of them around the propagation axis is also evident. Numerical results are verified by experiments.

Reversing the persistent current of particles in a driven optical ring lattice

We study the dynamics of persistent bosonic currents in closed-loop atom circuits in the form of ring lattices and under the action of time periodic driving. The closed-loop atom circuits are described by a Bose-Hubbard model in the presence of a Peierls phase and with periodic boundary conditions. We find that the motion of matter waves can be controlled with the help of an external driving only applied in one site of the ring lattice. For tuned values of the interaction strength between particles, we show that there exists a frequency range of the external driving where not only suppression but also reversion of the persistent bosonic currents is achieved. Applications of our results are discussed.

基于计算全息的光环晶格阵列研究

基于计算全息的光环晶格阵列研究

Self-healing property of optical ring lattice

We generate experimentally optical ring lattice structures which are the superposition of two coaxial Laguerre-Gaussian modes with common waist position and waist parameter. Although these structures are not diffraction-free, they show self-healing property. This self-reconstruction of the ring lattice can be understood by looking into the transverse energy flow at different z planes. The experimental results are verified by the numerical simulations.

Scheme for implementing atomic multiport devices

Multiport generalizations of beam splitters are the key component in multipath interferometers, which are important in a range of quantum state engineering and precision measurement schemes. Here we propose a straightforward method for implementing multiport devices for atoms trapped in optical ring lattices. These devices are interesting as atoms have certain properties (such as mass) that photons do not, and the ring configuration makes them useful for applications such as precision gyroscopes. We discuss how they could be employed in useful measurement schemes and investigate how practical considerations limit the size of the devices that can be achieved by this method.

Macroscopic superposition states in rotating ring lattices

We investigate the effects of rotation on one-dimensional ultracold bosons confined to optical ring lattices. First, we show that there exists a critical rotation frequency at which the ground state of a weakly interacting and integer-filled atomic gas is fragmented into a macroscopic superposition state with different circulation. Second, we point out several advantages of using slightly non-uniform ring lattices. Finally, we demonstrate that different quasi-momentum states can be distinguished in time-of-flight absorption imaging and propose to probe correlations via the many-body oscillations induced by a sudden change in the rotation frequency.

Supercurrents in an atom-molecule gas in an optical ring lattice

Atom and molecule currents in a Fermi gas in the neighborhood of a Feshbach resonance are studied in a one-dimensional optical ring lattice by directly diagonalizing small models. A rotational analogy of flux quantization is used to show that fraction of the current is carried by particles with twice the mass of an atom, which suggests pairing and superfluidity.