Restoring and tailoring very high dimensional spatial entanglement of a biphoton state transmitted through a scattering medium

TL;DR

This paper demonstrates the experimental restoration and control of very high-dimensional spatial entanglement in biphoton states transmitted through a scattering medium by measuring the transmission matrix and applying phase masks.

Contribution

It introduces a method to retrieve and manipulate high-dimensional biphoton entanglement after passing through a complex scattering medium using transmission matrix measurement and phase mask control.

Findings

Successfully retrieved a biphoton state with dimensionality of 8000.

Restored and manipulated the momentum correlations of entangled photons after scattering.

Used phase masks derived from the transmission matrix to control entanglement properties.

Abstract

We report experimental results where a momentum entangled biphoton state with a giant dimensionality of 8000 is retrieved and manipulated when only one photon of the pair is transmitted through a thin scattering medium. For this purpose, the transmission matrix of the complex medium is first measured with a phase-shifting interferometry measurement method using a spatial light modulator (SLM) illuminated with a laser source. From this matrix, different phase masks are calculated and addressed on the SLM to spatially control the focusing of the laser through the complex medium. These same masks are used to manipulate the phase of the biphoton wave function transmitted by the thin diffuser in order to restore and control in the same way the momentum correlations between the far-field images of twin beams issued from strongly spatial-multi-mode spontaneous parametric down conversion.