Fig. 1
From: Experimental extractable work-based multipartite separability criteria
a Experimental setup for the extractable work-based inseparability of bipartite states: The entangled photon source uses a 1.5-mm thick β Barium-Borate crystal pumped with 100 mW of laser at 355 nm, in conjunction with a spherical mirror (M), and delivers approximately 200 coincidence/s through 5 nm full width at half maximum interference filters. Details on the source can be found in ref. 31. We encode the logical states of each qubit in the horizontal and vertical polarization states |H〉 and |V〉 of each photon. Using quantum state tomography, we estimate a fidelity F = 0.961 ± 0.007 of the entangled resource with the maximally entangled state \(\frac{1}{{\sqrt 2 }}\) (|HH〉 + |VV〉). The corresponding value of tangle is T = 0.911 ± 0.008.34 The relative weight (\(\cos \varphi \)) of the two polarization contributions in such state can be tuned by the quarter waveplate (QWP m) in the source. One of the photons passes through a depolarizing channel, consisting of two LCs and the associated control electronics, which selects the value of μ. Finally, polarization measurements are performed at a polarization-analysis module consisting of a QWP, a HWP, a PBS, and an APD per mode. We also show the single-mode fibers used to convey the photonics signal to the polarization analysis module. Inset: measured W ρ (θ, θ) as a function of the measurement angle θ for state |ρ〉 with \(\cos \varphi = 0.85\), and μ = 0.98 (blue); \(\cos \varphi = 0.62\), and μ = 0.98 (purple); \(\cos \varphi = 0.62\), and μ = 0.51 (red). b Experimental setup for a GHZ-Cluster state. c Analogous setup for a W-type resource
