Detecting quantumness in uniform precessions

TL;DR

This paper introduces protocols to detect nonclassical states in quantum systems undergoing uniform precession, extending previous work to new systems and identifying a gap between classical and quantum expectations for various spin systems.

Contribution

The authors develop new protocols for detecting quantumness in systems with uniform precession, extending Tsirelson's work to finite-dimensional spins and harmonic oscillators.

Findings

Protocols successfully detect nonclassicality in various quantum systems.

A gap between classical and quantum expectations is found for spins with j ≥ 3/2.

Extension of Tsirelson's work to finite-dimensional spin systems.

Abstract

Building on work by Tsirelson, we present a family of protocols that detect the nonclassicality of suitable states of a single quantum system, under the sole assumption that the measured dynamical observable undergoes a uniform precession. The case of the harmonic oscillator was anticipated in the work by Tsirelson, which we extend. We then apply the protocols to finite-dimensional spins that undergo uniform precession in real space and find a gap between the classical and the quantum expectations for every $j\geq \frac{3}{2}$ (excluding $j=2$).