Necessary Condition for Steerability of Arbitrary Two-Qubit States with Loss

TL;DR

This paper derives a necessary condition for the steerability of two-qubit states considering qubit loss, aiding the understanding of one-way steering phenomena in experimental quantum physics.

Contribution

It introduces a new theoretical criterion for two-qubit steerability under loss, extending the understanding of quantum steering in practical scenarios.

Findings

Derived a necessary condition for steerability with qubit loss

Applied the condition to recent experimental one-way steering data

Enhanced understanding of loss effects on quantum steering

Abstract

Einstein-Podolsky-Rosen steering refers to the quantum phenomenon whereby the state of a system held by one party can be "steered" into different states at the will of another, distant, party by performing different local measurements. Although steering has been demonstrated in a number of experiments involving qubits, the question of which two-qubit states are steerable remains an open theoretical problem. Here, we derive a necessary condition for any two-qubit state to be steerable when the steering party suffers from a given probability of qubit loss. Our main result finds application in one-way steering demonstrations that rely upon loss. Specifically, we apply it to a recent experiment on one-way steering with projective measurements and POVMs, reported by Wollmann et. al. [Phys. Rev. Lett., 116, 160403 (2016)].