Symmetry enforced entanglement in maximally mixed states

Understand

Entanglement in quantum many-body systems is typically fragile to interactions with the environment.

• Generic unital quantum channels, for example, have the maximally mixed state with no entanglement as their unique steady state.
• However, we find that for a unital quantum channel that is `strongly symmetric', i.e.
• it preserves a global on-site symmetry, the maximally mixed steady state in certain symmetry sectors can be highly entangled.