Curator's Take
AI Commentary
This article overturns the conventional view that heat merely destroys quantum correlations by showing that an SU(2) non‑Abelian conservation law can turn local thermal fluctuations into a macroscopic source of distillable entanglement, scaling as half a bit per qubit even at high temperature. The result builds on recent work exploiting symmetry‑protected subspaces and adds a concrete protocol for spin chains where the global singlet constraint locks large irreducible representations, offering a rare example of thermally activated long‑range quantum resources. While the effect relies on strict global‑singlet preparation and idealized spin models, it suggests new routes to robust entanglement distribution in noisy platforms that respect non‑Abelian symmetries.
— Mark Eatherly
Summary
Thermal noise ordinarily suppresses quantum entanglement. We show that a strong non-Abelian conservation law can convert local thermal fluctuations into an unbounded operational resource. For a broad class of finite-range $SU(2)$-invariant spin chains restricted to the global-singlet sector, an explicit representation-space protocol yields $Y_N=\frac12\log_2 N+O_β(1)$, and hence $E_{\mathrm{D}}\geq Y_N$, throughout a finite high-temperature interval. Local thermal fluctuations produce subsystem spins $j\sim\sqrt N$, whose globally locked irreducible representations contain $\log_2(2j+1)\sim\frac12\log_2N$ ebits. An exactly solvable dimer chain exhibits a sharper effect: its zero-temperature state is unentangled across the cut, whereas every fixed $T>0$ produces $E_{\mathrm{D}}=\frac{1}{2}\log_2 N+C(T)+o(1)$, with crossover scale $T_*(N)\simΔ/\ln N$. Exact diagonalization of a nonintegrable chain is consistent with the predicted scaling. Thus heating can activate system-size-diverging distillable entanglement across a macroscopic bipartition when thermalization is confined by a non-Abelian conservation law.