  Tomographic reconstruction of the many-body quantum state of a scalable qubit
system is of paramount importance in quantum computing technologies. However,
conventional approaches which use tomographically orthogonal base measurements
require precise and individual qubit controls which are often experimentally
daunting. Here, we propose, as a quantum-mechanically robust alternative, to
use configurable ancillas of which the continuously-tunable interactions can
generate independent base measurements tomographically sufficient for the
quantum state reconstruction of the system of interest. Experimental tests are
performed for Rydberg atom arrays in $N$-body $W$ states, of which the results
demonstrate reliable high-fidelity full quantum state reconstruction of the
proposed method.
