Bare-Excitation Ground State of a Spinless-Fermion -- Boson Model and $W$-State Engineering in an Array of Superconducting Qubits and Resonators

This work unravels an interesting property of a one-dimensional lattice model that describes a single itinerant spinless fermion (excitation) coupled to zero-dimensional (dispersionless) bosons through two different nonlocal-coupling mechanisms. Namely, below a critical value of the effective excitation-boson coupling strength the exact ground state of this model is the zero-quasimomentum Bloch state of a bare (i.e., completely undressed) excitation. It is demonstrated here how this last property of the lattice model under consideration can be exploited for a fast, deterministic preparation of multipartite $W$ states in a readily realizable system of inductively-coupled superconducting qubits and microwave resonators.
Comment: final, published version; for a closely related realization of W states using Rydberg-dressed qubits, see arXiv:2101.11232 [ Phys. Rev. A 103, 022410 (2021) ]; for a non-technical summary of both works, see http://www.iap.tu-darmstadt.de/tqp/grp_stojanovic/Wentangle_PopularSummary.pdf