Experimental Sample-Efficient and Device-Independent GHZ State Certification
The work experimentally demonstrated device-independent certification for a single copy of a four-party GHZ state without assuming independent and identical copies from an IID source. Using a Bell inequality test, researchers verified an extractability of $\Xi(\tilde{\sigma}_c, |GHZ\rangle) \geq 0.896$ with high confidence (1 - $\delta = 0.99$), proving the protocol's validity for resource certification.