Quantum state interferography with heralded single photons

Abstract

Quantum state tomography is the standard method used for quantum state reconstruction. Recently, a new technique called, quantum state interferography, has been introduced for the direct single-shot measurement of the quantum state of a qubit [Phys. Rev. Lett. 125 (2020) 123601]. In the present work, we report a first-of-its-kind experimental demonstration of quantum state interferography of legitimate single photon polarization states derived from spontaneous parametric down conversion source. Further, we provide a more general and a simpler mathematical treatment of the QSI technique. While the theoretical treatment with d-dimensional state vectors in the earlier work is limited only to pure qudits, our approach readily lends itself to the case of mixed qudit systems. The basic arguments and the results of this extension are presented with a qutrit state as an example.