Quantum states weakly linked at low energy levels

Samuel J. Garratt and Dmitry A. Abanin of Princeton University, along with colleagues at École Polytechnique Fédérale de Lausanne and Google Research, have established new limits on the entanglement of quantum states. Their work reveals that entanglement entropies of subsystems comprising approximately half of a larger system are bounded by a formula linking them to the thermal entropies of two fictitious systems at the same temperature. The researchers demonstrate that ground states with zero-temperature thermal entropies scaling with surface areas, rather than volume, are demonstrably area-law entangled. These findings provide a pathway to translate thermodynamic data into constraints on pure-state entanglement for models of quantum matter…