Reconfigurable circuit for mode tunable topological quantum structured light

TL;DR

This paper presents a reconfigurable optical device that generates high-purity, topologically structured quantum light, enabling advanced quantum information applications with improved robustness and adaptability.

Contribution

It introduces a compact, self-locking interferometer integrating digital spatial light modulators for high-fidelity, reprogrammable topological quantum structured light generation.

Findings

Achieved high-fidelity mapping of spatial-mode entanglement.

Demonstrated reprogrammable topological entanglement with digital control.

Enabled reliable generation of quantum-structured light at the single-photon level.

Abstract

Structured light in the quantum regime has garnered considerable attention due to the opportunities it offers when mixing light's internal degrees of freedom, for high-dimensional and multi-dimensional quantum states of light. A popular example is to harness polarisation and spatial entangled photons with a shared topological invariant that is robust against numerous families of noisy quantum channels. Yet, producing such states with high purity and adaptability remains challenging. Here we introduce a compact, self-locking Mach-Zehnder interferometer that integrates digital spatial light modulators with static beam displacers to map spatial-mode entanglement from a parametric down-conversion source onto topological entanglement with high fidelity. The device also mimics the action of a reprogrammable controlled-unitary gate, digitally driven by the spatial light modulator. This approach is an enabling platform and provides a practical route to generating reliable, high-purity quantum-structured light with topological features, both at the single-photon level and as entangled states, a direction of growing topical interest.