Methods for Parallel Assembly of Arbitrary Defect-Free Atom Arrays
Opportunity
Optical tweezers quickly emerged as an indispensable tool that can be used for a variety of different applications in chemistry and biology since its introduction in 1986. In 2018 Arthur Ashkin won the Nobel Prize in Physics “for the optical tweezers and their application to biological systems”. In practice, optical tweezers are capable of manipulating nanometer and micron-sized dielectric particles by exerting extremely small forces via a highly focused laser beam.
Recently, optical tweezer arrays with individually trapped atoms have emerged as a promising platform for studies of quantum many-body physics, quantum information processing, and metrology. These atom arrays offer the key advantages of rapid loading times, ground-state cooling, and generation of defect-free arrays in arbitrary geometries. However, it is challenging to generate arbitrary, large-scale and defect-free neutral atom arrays.
This invention presents the methods for assembling arbitrary defect-free arrays with a novel parallel sort-and-compression algorithm (PSCA). The PSCA starts from atoms stochastically loaded into a two-dimensional base array of optical traps and uses multiple mobile tweezers to simultaneously rearrange atoms into their target sites. The algorithm avoids coupling among rows and among columns and naturally ensures collision-free moves.
Technology
PSCA achieves an efficient collision-free atom-sorting process via two steps: first, atoms are redistributed among different columns such that each column has the same number of atoms as required in the target array; second, each column is compressed to fill the defects within the target array. The two-step process can be repeated to improve the success probability of generating a defect-free array.
PSCA is designed to efficiently rearrange a randomly filled two-dimensional array (“base array”) of single atoms into a target array of arbitrary geometry in real time, within 60-200 milliseconds. The rearrangement is accomplished using a pair of acousto-optic deflectors, which can steer a given optical tweezer to a specific base array site, pick an atom up, transport the atom along the rows or columns of the base array, and finally release the atom into the desired site. These steering optical tweezers are known as mobile tweezers. Since atoms have a finite lifetime in the array, rearrangement efficiency is assessed based on the rearrangement time, or equivalently the number of moves needed, where short rearrangement times or minimal moves are favored. The key novelty of the PSCA lies in its ability to invoke multiple mobile tweezers simultaneously and move the atoms in a way that naturally avoids atom collisions.
Figure 1. Comparison of the multitweezer PSCA against the single-tweezer linear sum assignment problem (LSAP) algorithm. (a) Key steps taken by the PSCA to form a defect-free kagome lattice from a randomly filled array. The filled circles denote atoms while the arrows denote the action taken by the mobile tweezers at various timestamps marked by t_i. (b) Simulation results for the PSCA and LSAP algorithms when used to rearrange randomly filled arrays into compact target arrays of various sizes..
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