A technical guide to quantum computing hypervisors and metro-scale quantum key distribution — what isolation and multi-tenancy mean on hardware where a neighboring workload's crosstalk is a security concern, not just a performance one.
A classical hypervisor isolates one tenant's workload from another by keeping their memory and CPU cycles from overlapping. On quantum hardware, a neighboring circuit does not need to touch your data to affect your result — stray microwave crosstalk between adjacent qubits can shift a phase and corrupt a computation with no data ever having been shared at all, which is why quantum multi-tenancy has to reason about physical proximity on the chip, not just logical access control.