Quantum communication and mixed-state order in decohered symmetry-protected topological states

Long-range quantum entanglement can be distilled from certain symmetry-protected topological (STP) states of matter. Here, the authors investigate whether SPT states, subject to decoherence, can still be used for the transmission of coherent quantum information, and link this capability to quantum order in the resulting mixed quantum many-body states. This connection reveals new sources of decoherence which permit the use of SPT states as a resource for information transmission, offering new perspectives on entanglement distillation and on the resilience of mixed-state symmetry-protected order.