Fourier processing of quantum light

TL;DR

This paper demonstrates that classical Fourier optical processors can shape and analyze quantum correlations of entangled photons, enabling complex quantum state manipulation and information retrieval.

Contribution

It introduces the use of classical Fourier masks for quantum light shaping and experimentally verifies their effectiveness with entangled photon pairs.

Findings

Sinusoidal phase masks create intricate quantum correlation patterns.

Periodic Zernike-like filters recover phase information lost in correlations.

Quantum correlations can be manipulated using classical Fourier processing techniques.

Abstract

It is shown that a classical optical Fourier processor can be used for the shaping of quantum correlations between two or more photons, and the class of Fourier masks applicable in the multiphoton Fourier space is identified. This concept is experimentally demonstrated using two types of periodic phase masks illuminated with path-entangled photon pairs, a highly non-classical state of light. Applied first were sinusoidal phase masks, emulating two-particle quantum walk on a periodic lattice, yielding intricate correlation patterns with various spatial bunching and anti-bunching effects depending on the initial state. Then, a periodic Zernike-like filter was applied on top of the sinusoidal phase masks. Using this filter, phase information lost in the original correlation measurements was retrieved.