  Single atoms movable from one place to another would enable a flying quantum
memory that can be used for quantum communication and quantum computing at the
same time. Guided atoms, e.g., by optical tweezers, provide a partial solution,
but the benefit of flying qubits could be lost if they still interact with the
guiding means. Here we propose and experimentally demonstrate freely-flying
atoms that are not guided but are instead thrown and caught by optical
tweezers. In experiments, cold atoms at 40 micro Kelvin temperature are thrown
up to a free-flying speed of 0.65 m/s over a travel distance of 12.6 micrometer
at a transportation efficiency of 94(3)%, even in the presence of other optical
tweezers or atoms en route. This performance is not fundamentally limited but
by current settings of optical tweezers with limited potential depth and width.
We provide a set of proof-of-principle flying atom demonstrations, which
include atom transport through optical tweezers, atom arrangements by flying
atoms, and atom scattering off optical tweezers. Our study suggests possible
applications of flying atoms, not only in fundamental studies such as
single-atom low-energy collisions, but also non-photon quantum communication
and flying-qubit-based quantum computing.
