Fig. 1: Overview on the QREAL architecture.

a The hardware of a general quantum receiver composed of rounds of processing. The jth processing round entails a variational quantum circuit represented by the unitary operation \(\hat U_j\) configured by the parameter set α_j, ancillary states \(\hat \rho _{s_j}\), and measurement apparatus \({{{\mathcal{M}}}}_j\). b The control logic comprised of a decision tree and a decision table. Blue lines show one possible path toward the output. Quantum-receiver output y is determined by the sequence of measurement outcomes, tied to a unique path in the decision tree. c The QREAL formulator consisting of four modules (clockwise) as one iteration in the learning process. The control logic optimized by the QREAL formulator is compiled and built into the classical processor