Stability of Flip and Exchange Symmetric Entangled State Classes under Invertible Local Operations

TL;DR

This paper investigates the stability of flip and exchange symmetric entangled states under invertible local operations, revealing that entanglement classes are stable at their boundaries due to decreasing success probabilities.

Contribution

It introduces a systematic method to classify FES states into equivalence classes under ILO and demonstrates their stability at class boundaries.

Findings

Equivalence classes of FES states can be systematically determined.

Boundary states between classes exhibit decreasing success probability.

Entanglement classes are stable under invertible local operations.

Abstract

Flip and exchange symmetric (FES) many-qubit states, which can be obtained from a state with the same symmetries by means of invertible local operations (ILO), constitute a one-parameter family of curves in the Hilbert space. Eigenstates of FES ILOs correspond to vectors that cannot be transformed to other FES states. This means equivalence classes of states under ILO can be determined in a systematic way for an arbitrary number of qubits. More important, for entangled states, at the boundaries of neighboring equivalence classes, one can show that when the fidelity between the final state after an ILO and a state of the neighboring class approaches unity, probability of success decreases to zero. Therefore, the classes are stable under ILOs.