Frustration-free control for quantum-state preparation: an exact first-passage theory

arXiv:2611.13094v1 Announce Type: new Abstract: Quantum circuits based on local measurements and feedback can autonomously prepare and stabilize entangled many-body states. In frustration-free control, the target manifold is specified by local constraints, whose violations are detected by measurement and removed by feedback. We develop an exact theory of this mechanism for the preparation of Dicke states of $N_q$ qubits. Dicke states span the permutation-symmetric subspace, one per magnetization sector. Local singlet projectors define the constraints and detect departures from permutation symmetry.