Steering a single system sequentially by multiple observers

TL;DR

This paper investigates the limits of multiple observers sequentially steering a quantum system, revealing scenarios where the monogamy restriction can be surpassed with specific measurement settings.

Contribution

It introduces a framework for multiple observers sequentially steering a quantum system, surpassing traditional monogamy limits under certain measurement conditions.

Findings

Two Bobs can steer Alice's system beyond monogamy restrictions.

Three Bobs can steer Alice's system using a three-settings linear steering inequality.

Conjecture that at most n Bobs can demonstrate steering with n-settings inequalities.

Abstract

Quantum mechanics puts a restriction on the number of observers who can simultaneously steer another observer's system, known as the monogamy of steering. In this work we find the limit of the number of observers (Bobs) who can steer another party's (Alice's) system invoking a scenario where half of an entangled pair is shared between a single Alice in one wing and several Bobs on the other wing, who act sequentially and independently of each other. When all the observers measure two dichotomic observables, we find that two Bobs can steer Alice's system going beyond the monogamy restriction. We further show that three Bobs can steer Alice's system considering a three-settings linear steering inequality, and then conjecture that at most $n$ Bobs can demonstrate steering of Alice's system when steering is probed through an $n$-settings linear steering inequality.