Relatively simple quantum computer design uses single atom to manipulate photons; could be constructed with currently available components
https://news.stanford.edu/2021/11/29/simpler-design-quantum-computers/ "design consists of two main sections: a storage ring and a scattering unit... Because the atom and the photon are entangled, manipulating the atom also affects the state of the photon... Because you can control the way the atom and photons interact, the same device can run many different quantum programs... if you want to change the program that’s running... you don’t need to change the hardware – you just need to give the machine a different set of instructions" Related: Super-Resolution Imaging of a Single Cold Atom on a Nanosecond Timescale https://scitechdaily.com/super-resolution-imaging-of-a-single-cold-atom-on-a-nanosecond-timescale/