Hierarchical Verification of Non-Gaussian Coherence in Bosonic Quantum States

TL;DR

This paper introduces a hierarchical framework for verifying non-Gaussian coherence in bosonic quantum states, crucial for quantum technologies, using optical states with high purity to evaluate number state coherences.

Contribution

It presents the first detailed hierarchical framework for assessing non-Gaussianity in bosonic states, adaptable to various quantum applications.

Findings

Framework effectively evaluates non-Gaussian coherence thresholds.

Application to high-purity optical states demonstrates practical utility.

Framework can be extended to diverse bosonic quantum states.

Abstract

Non-Gaussianity, a distinctive characteristic of bosonic quantum states, is pivotal in advancing quantum networks, fault-tolerant quantum computing, and high-precision metrology. Verifying the quantum nature of a state, particularly its non-Gaussian features, is essential for ensuring the reliability and performance of these technologies. However, the specific properties required for each application demand tailored validation thresholds. Here, we introduce a hierarchical framework comprising absolute, relative, and qubit-specific thresholds to assess the non-Gaussianity of local coherences. We illustrate this framework using heralded optical non-Gaussian states with the highest purities available in optical platforms. This comprehensive framework presents the first detailed evaluation of number state coherences and can be extended to a wide range of bosonic states.