Fig. 3: Polarization analysis of photon pairs.
From: A tunable transition metal dichalcogenide entangled photon-pair source
a Polarization-resolved second-harmonic measurement (blue circles) for the rotation of the pump polarization angle φp,SHG, and parallelly polarized, co-rotating analyzer. The black curve is a fit with the theoretically expected dependence \({I}_{{{{\rm{SHG}}}}}\propto {\sin }^{2}(3{\varphi }_{{{{\rm{p,SHG}}}}})\). The armchair (AC), and zigzag (ZZ) directions are marked with dashed brown and cyan lines, respectively. b Measured photon-pair rate for rotation of the SPDC pump polarization angle φp for unpolarized detection. The black curve marks a fit with the theoretically expected constant function. c Measured photon-pair rate for rotating pump polarization φp and detection through a co-rotating, perpendicularly oriented (blue circles), and parallelly oriented (purple squares) analyzer. In both cases, the expected \({R}_{{{{\rm{SPDC}}}}}\propto {\sin }^{2}(3{\varphi }_{{{{\rm{p}}}}})\) dependence (black curve) is overlayed. d–f Measured photon-pair rates for the rotating pump polarization φp and an analyzer fixed at d φpol = 110° (20° offset from AC-axis), e φpol = 55° (25° offset from AC-axis), and f φpol = 50° (20° offset from AC-axis). The dash-dotted black line marks the direction of the analyzer transmission axis, the solid dashed line is the theoretically expected dependence \({R}_{{{{\rm{SPDC}}}}}\propto {\sin }^{2}(2{\varphi }_{{{{\rm{pol}}}}}+{\varphi }_{{{{\rm{p}}}}})\). Error bars mark the standard deviation based on the Poissonian statistics of SPDC coincidence detection.
