Quantum Storage of Three-Dimensional Orbital-Angular-Momentum Entanglement in a Crystal

TL;DR

This paper demonstrates the successful quantum storage of three-dimensional orbital-angular-momentum entanglement in a rare-earth-ion-doped crystal, confirming high fidelity, entanglement preservation, and multimode capacity for advanced quantum communication.

Contribution

It introduces a method for storing high-dimensional orbital-angular-momentum entanglement in a solid-state crystal with high fidelity and multimode capacity, advancing quantum memory technology.

Findings

Bell inequality violation after storage confirms entanglement preservation

Memory fidelity measured at 0.993, indicating high accuracy

Memory supports 51 spatial modes, enabling high-dimensional quantum information processing

Abstract

Here we present the quantum storage of three-dimensional orbital-angular-momentum photonic entanglement in a rare-earth-ion-doped crystal. The properties of the entanglement and the storage process are confirmed by the violation of the Bell-type inequality generalized to three dimensions after storage ($S=2.152\pm0.033$). The fidelity of the memory process is $0.993\pm0.002$, as determined through complete quantum process tomography in three dimensions. An assessment of the visibility of the stored weak coherent pulses in higher-dimensional spaces, demonstrates that the memory is highly reliable for 51 spatial modes. These results pave the way towards the construction of high-dimensional and multiplexed quantum repeaters based on solid-state devices. The multimode capacity of rare-earth-based optical processor goes beyond the temporal and the spectral degree of freedom, which might provide a useful tool for photonic information processing.