Quantum Repeater Architectures Based on Quantum Memories and Photonic Encoding

ended

At the heart of all anticipated network-based quantum applications lies the requirement to establish quantum communication between individual network nodes over long distances. Quantum communication exceeding 100 km requires so-called quantum repeaters to extend communication beyond this limit. Mainly two types of quantum repeater schemes are being investigated: Quantum-memory-based schemes for long-distant entanglement generation and photonic encoding-based schemes for fast secure quantum communication. To date, both schemes have only been considered individually, however, a hybrid approach could overcome their distinct limitations and benefit from individual advantages. How such a system could be realized remains an open question. This project addresses the challenges, benefits, and resource requirements for a hybrid architecture of interconnected photonic-cluster-state-based and quantum-memory-based quantum repeaters. In a theoretical study, cost parameters of such a hybrid quantum repeater for realistic system properties will be determined for the first time. Experimentally, electron spin coupled quantum dot single photon sources will be employed as resource for multi-photon cluster state generation. In parallel, a new type of quantum memory—the SnV defect in diamond, will serve to demonstrate remote entanglement. Finally, these two disparate systems will be interconnected via frequency conversion and Bell-measurements—to demonstrate cross-platform entanglement. Investigating for the first time an interconnected system of two disparate solid-state resources for quantum communication will stimulate ground-breaking research towards hybrid quantum repeater architectures. All three objectives will benefit from the PI’s recent expertise in spectroscopy, spin control, and nanofabrication of gallium arsenide quantum dots and diamond defect centres in integrated photonic structures.