Interferometric imaging of amplitude and phase of spatial biphoton states

Abstract

High-dimensional biphoton states are promising resources for quantum applications, ranging from highdimensional quantum communications to quantum imaging. A pivotal task is fully characterising these states, which is generally time-consuming and not scalable when projective measurement approaches are adopted. However, new advances in coincidence imaging technologies allow for overcoming these limitations by parallelising multiple measurements. Here, we introduce biphoton digital holography, in analogy to off-axis digital holography, where coincidence imaging of the superposition of an unknown state with a reference one is used to perform quantum state tomography. We apply this approach to single photons emitted by spontaneous parametric down-conversion in a nonlinear crystal when the pump photons possess various quantum states. The proposed reconstruction technique allows for a more efficient (3 order-of-magnitude faster) and reliable (an average fidelity of 87%) characterisation of states in arbitrary spatial modes bases, compared with previously performed experiments. Multi-photon digital holography may pave the route toward efficient and accurate computational ghost imaging and high-dimensional quantum information processing.

Intensity interferometry for holography with quantum and classical light

“…However, thanks to recent advances in camera technology, it is now possible to measure intensity correlations at the single-photon level in a spatially resolved manner. While this has mainly been demonstrated with photonpair sources (24)(25)(26)(27)(28)(29)(30)(31)(32), it also facilitates quantum-inspired imaging techniques that are applicable to classical light (33)(34)(35)(36)(37)(38)(39)(40)(41) and has led to a renewed interest in using intensity correlations for astronomy (42)(43)(44)(45).…”

Characterisation of topological photons

“…This approach involves spatially resolved coincidence measurements, which are an upgrade from the classical method of spatially resolved single photon measurement. Bi-photon digital holography has been shown to speed up quantum state tomography by three orders of magnitude and improve the state reconstruction fidelity from 60% to 87% for high-dimensional bi-photon Hilbert space [3].…”