Superposition is the ability for atoms or ions to be in multiple states simultaneously and entanglement is a unique shared connection between 2 qubits. There are many ways to produce entanglement, including bringing two particles close together, perform an operation to entangle them and move them apart again. No matter how far apart they are, they will always yield the same outcome. The operations can be performed by cooling the atoms or ions to near absolute zero, and manipulating them, with precision lasers within a UHV chamber.
The internal volume of such UHV chambers can be as small as a few cubic centimeters, but no matter what the size, the vacuum technology exists to achieve the conditions necessary. Ion sputter pumps e.g. the “small profile” TiTan range by Gamma Vacuum, are an accepted method of producing and maintaining UHV conditions with pumping speeds ranging from the miniature 0.2 l/s up to 75 l/s. With such pumps, and optionally a titanium sublimation pump (TSP) used in conjunction to boost pumping, a vacuum level more rarefied than outer space can be achieved.