A photonic quantum interface for hybrid quantum network

TL;DR

This paper demonstrates the generation of non-degenerate, narrow-band polarization-entangled photon pairs suitable for hybrid quantum networks, facilitating integration of different quantum systems for communication and computation.

Contribution

First demonstration of non-degenerate narrow-band entangled photon pairs generated via cavity-enhanced spontaneous parametric down-conversion for hybrid quantum networks.

Findings

Photon pairs have bandwidths of 9 MHz and 9.5 MHz at 935 nm and 880 nm.

Entanglement fidelity of 89.6% with Bell state.

Strong violation of Bell inequality confirming entanglement.

Abstract

The hybrid quantum network, a universal form of quantum network which is aimed for quantum communication and distributed quantum computation, is that the quantum nodes in it are realized with different physical systems. This universal form of quantum network can combine the advantages and avoid the inherent defects of the different physical system. However, one obstacle standing in the way is the compatible photonic quantum interface. One possible solution is using non-degenerate, narrow-band, entangled photon pairs as the photonic interface. Here, for the first time, we generate nondegenrate narrow-band polarization-entangled photon pairs in cavity-enhanced spontaneous parametric down-conversion process. The bandwidths and central wavelengths of the signal and idler photons are 9 MHz at 935 nm and 9.5 MHz at 880 nm, which are compatible with trapped ion system and solid-state quantum memory system. The entanglement of the photon source is certified by quantum state tomography, showing a fidelity of 89.6% between the generated quantum state with a Bell state. Besides, a strong violation against Bell inequality with 2.36+/-0.03 further confirms the entanglement property of the photon pairs. Our method is suitable for the hybrid quantum network and will take a big step in this field.