Product update
Optics Bench adds single-qubit state tomography
Prepare a polarization qubit with a QHQ wave-plate gate, then reconstruct it from six projective measurements - including heralded photons from an SPDC source.
The Optics Bench on QuantumSimulation can now reconstruct the state of a polarization qubit.
A QWP-HWP-QWP wave-plate stack acts as a universal single-qubit gate. A tomography analyzer - a quarter-wave plate, a half-wave plate, a polarizing beam splitter and two detectors - then projects the qubit onto the H, V, D, A, R and L states in turn. From those six measurements the bench reconstructs the density matrix, the Bloch vector, the purity and the fidelity to the nearest pure state.
It also works with photon pairs: detect one photon of an SPDC pair as a herald, and the partner photon is reconstructed from coincidence counts. With an entangled source, the heralded photon comes out maximally mixed - each photon of an entangled pair is individually unpolarized.
Try the Single-qubit gate + tomography and Heralded SPDC tomography examples.