Pockels Cell Phase Shifter 2D: Mach–Zehnder Interferometer Schematic

This 2D schematic drives a real Pockels-cell electro-optic phase shifter — the linear electro-optic effect used in every practical quantum phase shifter — sitting in one arm of a Mach–Zehnder interferometer. Dial the crystal drive voltage and its half-wave voltage V_π, or drag the phase vector directly, and watch the induced phase φ = φ₀ + πV/V_π steer single photons between two detectors: faint superposed pulses travel both arms simultaneously, and only at the recombining beamsplitter does each photon collapse into a click at D0 or D1, with live counts converging on the cos²(φ/2) / sin²(φ/2) interference law — plotted live alongside the schematic.