Is there a material that could be used as an insulator to reduce or eliminate interference between multiple qbits?
There are many architectures being worked on. One place to get started is with the work of Andrea Morello. This page at the SFU Physics website has links to some of his papers and those of others, published in major journals. https://www.sfu.ca/physics/newsevents/phys-events/2017/feb/event10.html