Nonlinear steering criteria for arbitrary two-qubit quantum systems

TL;DR

This paper introduces nonlinear steering criteria for two-qubit systems using Pauli measurements, which outperform linear and entropic criteria by certifying more steerable states without measurement optimization.

Contribution

It develops optimized nonlinear steering criteria applicable to all two-qubit states, improving detection capabilities over existing linear and entropic methods.

Findings

Certifies more steerable states than linear criteria

Works for arbitrary two-qubit states without measurement optimization

Can also verify entanglement in quantum systems

Abstract

By employing Pauli measurements, we present some nonlinear steering criteria applicable for arbitrary two-qubit quantum systems and optimized ones for symmetric quantum states. These criteria provide sufficient conditions to witness steering, which can recover the previous elegant results for some well-known states. Compared with the existing linear steering criterion and entropic criterion, ours can certify more steerable states without selecting measurement settings or correlation weights, which can also be used to verify entanglement as all steerable quantum states are entangled.