Self-referenced hologram of a single photon beam

TL;DR

This paper presents a novel interferometric method for fully characterizing the spatial structure of single photons by self-interference, eliminating the need for a reference photon, and demonstrates its effectiveness experimentally.

Contribution

The introduced technique allows complete spatial phase characterization of single photons using self-interference, a significant advancement over reference-based methods.

Findings

Successfully reconstructed the spatial phase of heralded single photons.

Demonstrated the feasibility of the method with experimental data.

Applicable to arbitrary pure spatial states of single photons.

Abstract

Quantitative characterization of the spatial structure of single photons is essential for free-space quantum communication and quantum imaging. We introduce an interferometric technique that enables the complete characterization of a two-dimensional probability amplitude of a single photon. Importantly, in contrast to methods that use a reference photon for the phase measurement, our technique relies on a single photon interfering with itself. Our setup comprises of a heralded single-photon source with an unknown spatial phase and a modified Mach-Zehnder interferometer with a spatial filter in one of its arms. The spatial filter removes the unknown spatial phase and the filtered beam interferes with the unaltered beam passing through the other arm of the interferometer. We experimentally confirm the feasibility of our technique by reconstructing the spatial phase of heralded single photons using the lowest order interference fringes. This technique can be applied to the characterization of arbitrary pure spatial states of single photons.