Emergent entanglement in loop-dressed spin-ensemble dynamics
Phys. Rev. A 113, 052418 – Published 8 May, 2026
DOI: https://doi.org/10.1103/v13l-7n3b
Abstract
Mesoscopic spin ensembles provide an experimentally accessible setting in which collective dipolar dynamics are easier to realize than architectures based on individually controlled spins, yet remain too large for exact many-spin treatments. We develop a spin coherent-state closed-time-path theory for coarse-grained spin packets that yields loop-dressed real-time dynamics together with a controlled Gaussian fluctuation sector. Within this treatment, the relevant reduced subsystem is the Gaussian state of the canonical tangent-plane packet modes. On the Jeener cube, the exact classical invariant manifold provides an exact null control, while away from that manifold the native packet dynamics generate pairwise entanglement together with positive full-inseparability scores in the retained Gaussian packet-mode description. Coherent loop dressing enhances these observables in a channel-dependent way, whereas dissipative dressing suppresses them. These results show that coarse packet theories can support emergent mesoscopic Gaussian entanglement and can identify which dressing channels strengthen or weaken it.
