Cold Matter Assembled Atom-by-Atom
  The realization of large-scale fully controllable quantum systems is an exciting frontier in modern physical science. We use atom-by-atom assembly to implement a novel platform for the deterministic preparation of regular arrays of individually controlled cold atoms. In our approach, a measurement and feedback procedure eliminates the entropy associated with probabilistic trap occupation and results in defect-free arrays of over 50 atoms in less than 400 ms. The technique is based on fast, real-time control of 100 optical tweezers, which we use to arrange atoms in desired geometric patterns and to maintain these configurations by replacing lost atoms with surplus atoms from a reservoir. This bottom-up approach enables controlled engineering of scalable many-body systems for quantum information processing, quantum simulations, and precision measurements. 
Manuel Endres, Hannes Bernien, Alexander Keesling, Harry Levine, Eric   R. Anschuetz, Alexandre Krajenbrink, Crystal Senko, ...
quant-ph cond-mat.quant-gas physics.atom-ph