Figure 1

(a) Histogram of infidelity for 3000 randomly selected entangled states and 3000 separable states for which SSQST was simulated. The Monte Carlo simulation used 18 000 total copies for each random state. (b) Comparison of experimental MUB tomography and SSQST for the maximally mixed state. The average value of the ratio of infidelity using the SSQST-estimated density matrix to that using MUB tomography was $1.49\pm 0.05$. (c) Comparison of experimental MUB tomography and SSQST for the state $(1/\sqrt{2})(|HH⟩+|VV⟩)$. The average ratio of infidelity for the two methods was $1.84\pm 0.06$. (d) Comparison of experimental MUB tomography and SSQST for $|HV⟩$. The infidelity ratio for the two tomography methods was $1.09\pm 0.4$. In (b)–(d) the solid line represents a fit to the SSQST data and the dotted line to the MUB QST data. The apparent crossing of the MUBs and SSQST lines in (d) is due to numerical errors at high $N$.Reuse & Permissions

Figure 2

Experimental apparatus for MUB state tomography. A nonlinear crystal (BBO) is pumped to produce pairs of spontaneous parametric down-conversion photons. LCWPs and HWPs rotate the state. Entangling measurements are made by using two-photon interference at a removable nonpolarizing beam splitter (BS), and these measurements can be rotated with HWPs, quarter wave plates (QWPs) and LCWPs to generate all necessary projections. For separable measurements the BS is removed and ordinary polarization analysis performed at the detectors using the polarizing beam splitters (PBS), HWPs, and QWPs.Reuse & Permissions