Characterizing quantum channels from local-unitary invariants

• URL: http://arxiv.org/abs/2606.03722v1
• Date: Tue, 02 Jun 2026 14:42:14 GMT
• Title: Characterizing quantum channels from local-unitary invariants
• Abstract summary: We introduce averaged local-unitary invariants, referred to as moments, obtained from Haar integrals over input states or unitaries.<n>These moments provide computable descriptions of how a quantum channel can create, preserve, or destroy bipartite entanglement.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We develop systematic frameworks for characterizing the entanglement properties of two-qubit channels beyond unitary settings. We introduce averaged local-unitary invariants, referred to as moments, obtained from Haar integrals over input states or unitaries. These moments provide computable descriptions of how a quantum channel can create, preserve, or destroy bipartite entanglement. We first show that second-order moments yield criteria for non-entangling and entanglement-breaking channels, which allow us to detect entanglement-creating and entanglement-preserving channels. We then demonstrate that higher-order moments can capture additional information and distinguish channels beyond second-order moments alone. Finally, we show that combinations of moments associated with different channel families improve the discrimination of locally inequivalent two-qubit unitaries.

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