Determination of spatial quantum states by using point diffraction interferometry

LORENA REBÓN; QUIMEY PEARS STEFANO; CLAUDIO IEMMI

Journal of Optics

IOP Publishing

Año: 2020 vol. 22

2040-8978

We present a method to reconstruct pure spatial qudits of arbitrary dimension d, which is basedon a point diffraction interferometer. In the proposed scheme, the quantum states are codified inthe discretized transverse position of a photon field, once they are sent through an apertureconsisting in d rectangular regions, with an extra region that provides a phase reference. Tocharacterize these photonic quantum states, the complete phase wavefront is reconstructedthrough a phase-shifting technique. Combined with a multipixel detector, the acquisition can beparallelized, and only four interferograms are required to reconstruct any pure qudit,independently of the dimension d. We tested the method experimentally, for reconstructingstates of dimension d=6 randomly chosen. A mean fidelity values of 0.95 is obtained.Additionally, we develop an experimental scheme that allows to estimate phase aberrationsaffecting the wavefront upon propagation, and thus improve the quantum state estimation. Inthat regard, we present a proof-of-principle demonstration that shows the possibility to correctthe influence of turbulence in a free-space communication, recovering mean fidelity valuescomparable to the propagation free of turbulence.