Hybrid quantum network with a direct telecom photonic interface

As quantum networks continue to grow in scale and complexity, interfacing distinct quantum systems is becoming ever more compelling. Such a hybrid network could leverage the unique capabilities of each node, offering both versatility and high efficiency in a single quantum network. Yet hybrid connections require both telecom interfaces for long-distance fiber links, and compensation for bandwidth mismatch between the platforms – thus often needing multiple stages of quantum frequency conversion and filtering, severely degrading the link efficiency. Here we identify two attractive quantum networking platforms with inherent compatibility, and develop their capabilities at a common telecom wavelength to allow a direct photonic interface that bypasses the need for quantum frequency conversion. At one end of the network, our photon source node uses phase-matched four-wave mixing in a warm rubidium ensemble to create entangled photon pairs. On the other end, our memory node is based on an atomic frequency comb in an erbium-doped yttrium orthovanadate crystal, which allows broadband, multimode storage of the photons. We present recent progress on developing and linking these two nodes, and discuss prospects for connecting to additional nodes with quantum processing capabilities.

*This work is supported by the NSF QLCI for Hybrid Quantum Architectures and Networks (NSF Award No. 2016136) and an NSF Career award (NSF Award No. 2238860).