Observation of the Symmetry-Protected Signature of 3-body Interactions

TL;DR

This paper presents an efficient method to detect 3-body interactions in quantum systems by exploiting symmetry-protected signatures, even when 2-body interactions are present and unknown.

Contribution

It introduces a novel technique using GHZ states and determinant measurements to identify 3-body interactions under symmetry constraints, advancing quantum process characterization.

Findings

Successfully detects 3-body interactions in the presence of unknown 2-body interactions.

Uses GHZ states for phase estimation to identify symmetry-protected signatures.

Scalable method with linear resource requirements relative to system size.

Abstract

Identifying and characterizing multi-body interactions in quantum processes remains a significant challenge. This is partly because 2-body interactions can produce an arbitrary time evolution, a fundamental fact often called the universality of 2-local gates in the context of quantum computing. However, when an unknown Hamiltonian respects a U(1) symmetry such as charge or particle number conservation, N-body interactions exhibit a distinct symmetry-protected signature known as the N-body phase, which fewer-body interactions cannot mimic. We develop and demonstrate an efficient technique for the detection of 3-body interactions despite the presence of unknown 2-body interactions. This technique, which takes advantage of GHZ states for phase estimation, requires probing the unitary evolution and measuring its determinant in a small subspace that scales linearly with the system size, making it an efficient approach.