Supersinglets can be self-tested with perfect quantum strategies

TL;DR

This paper demonstrates that supersinglet states of multiple particles can be uniquely identified and verified through a self-testing protocol that guarantees perfect quantum strategies, highlighting their distinctive nonlocal properties.

Contribution

The authors introduce a protocol that self-tests all supersinglet states, establishing their unique nonlocal signature and perfect quantum strategies for any dimension d ≥ 3.

Findings

Supersinglets can be self-tested with perfect quantum strategies.

The protocol uniquely identifies supersinglets among quantum states.

Supersinglets produce a distinct nonlocal signature for any dimension d ≥ 3.

Abstract

Supersinglets are states of spin-zero of $d \ge 3$ particles of $d$ levels. They are invariant under unitary transformations of the form $U^{\otimes d}$ and have applications in metrology, error protection, and communication. They also violate some specific Bell inequalities. However, none any of these applications {\em require} supersinglets nor do any of these Bell inequality violations capture the unique properties of the supersinglets. This leads to two questions. Question 1 is whether there exists a task that can be solved only with supersinglets. Question 2 is whether supersinglets can produce a unique $d$-partite, $d$-dimensional nonlocal signature. We answer both questions affirmatively by presenting a protocol that self-test all supersinglets by producing $d$-partite, $d$-dimensional {\em perfect} quantum strategies for any $d \ge 3$.