  Cooling and trapping of atoms by light has enabled one to build and
manipulate quantum systems at the single atom level. Such a bottom-up approach
becomes one of the fascinating challenges toward scalable and highly
controllable quantum systems, e.g., a large-scale quantum information machine.
Their implementation requires crucial pre-requisites: scalablity, site
distinguishability, and reliable single-atom loading into sites. The widely
adopted methods satisfies the two former conditions relatively well, but the
last condition, filling single atoms onto individual sites, relies mostly on
the probabilistic loading, implying that loading a pre-defined set of atoms in
given positions will be hampered exponentially. Two approaches are readily
thinkable to overcome this issue: increasing the single-atom loading efficiency
and relocating abundant atoms into unfilled positions. Realizing the relocation
is directly related to how many atoms can be transportable in a designer way.
Here, we demonstrate a dynamic holographic single-atom tweezers with
unprecedented degrees of freedom of 2N. In a proof-of-principle experiment
conducted with cold rubidium atoms, simultaneous rearrangements of N=9 single
atoms are successfully performed. This method may be further applicable to
deterministic N single-atom loading, coherent transport, and controlled
collisions.
