Instant single-photon Fock state tomography

Heralded single photons are prepared at a rate of 100 kHz via conditional measurements on polarizationnondegenerate biphotons produced in a periodically poled potassium-titanyl phosphate crystal. The singlephoton Fock state is characterized using high-frequency pulsed optical homodyne tomography with a fidelity of (57.6±0.1)%. The state preparation and detection rates allowed us to perform on-the-fly alignment of the apparatus based on real-time analysis of the quadrature measurement statistics.