Experimental test of rotational invariance and entanglement of photonic six-qubit singlet state

TL;DR

This paper experimentally verifies the rotational invariance and entanglement of a six-photon singlet state, demonstrating its potential for robust multi-party quantum communication with high fidelity and low error rates.

Contribution

It provides the first experimental validation of invariance properties and entanglement detection in a six-qubit singlet state, advancing multi-photon quantum state engineering.

Findings

Confirmed invariance properties match theoretical predictions

Detected strong entanglement with error rate below 6%

Showed the setup's stability for quantum communication protocols

Abstract

We experimentally test invariance properties of the six-photonic-qubits generalization of a singlet state. Our results clearly corroborate with theory. The invariance properties are useful to beat some types of decoherence. We also experimentally detect entanglement in the state using an appropriate witness observable, composed of local observables. Our results clearly indicate that the tested setup, which is very stable, is a good candidate for realization of various multi-party quantum communication protocols. The estimated fidelity of the produced state is very high: it reveals very strong EPR six-photon correlations of error rate below 6%.