What does "interdisciplinary" mean in the context of Quantum Computing?
"interdisciplinary" is just a 'buzzword' that essentially means that none of the traditional divisions of the sciences applies for the field. As this is the case with most recent serious research, this word is often vacuous.

As for quantum computing, practice is currently dominated by the Physicists. Theory is mostly for the CS people. They don't mix very well, as both think they know the other field while they in fact don't.