That landmark paper is available for free from arXiv:
DiVincenzo, D. P. (2000).
The physical implementation of quantum computation.
Notice that qubits cannot be physically realized like classical bits. Although it would be nice if they could, the reason they can't is also why we want them in the first place. Quantum algorithms exploit the lack of a single state in quantum systems. Yet these systems, whether they are photons or electrons or whatever, are "controlled" the same way quantum systems are in experiments: NMR, ion traps, etc. Quantum computing is not just using quantum mechanics but physically manipulating quantum systems in ways that we can use. Even when we are much more capable of this than we are now, quantum mechanics itself forbids us from storing qubits in some physical realization of "quantum RAM". The whole point of qubits is that they do not have a single state. Yet once they are measured/interfered with they will. Quantum algorithms exploit what quantum systems that cohere can do. As soon as we try to get information from or do anything with the physical quantum system used as a qubit, it is no longer a qubit.