  We propose and analyze a passive architecture for realizing on-chip, scalable
cascaded quantum devices. In contrast to standard approaches, our scheme does
not rely on breaking Lorentz reciprocity. Rather, we engineer the interplay
between pairs of superconducting transmon qubits and a microwave transmission
line, in such a way that two delocalized orthogonal excitations emit (and
absorb) photons propagating in opposite directions. We show how such cascaded
quantum devices can be exploited to passively probe and measure complex
many-body operators on quantum registers of stationary qubits, thus enabling
the heralded transfer of quantum states between distant qubits, as well as the
generation and manipulation of stabilizer codes for quantum error correction.
