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Quantum Repeater Architectures Based on Quantum Memories and Photonic Encoding

Project description

Going the distance may get a boost from a novel repeater architecture

The movement of electrons and photons underlies the transfer of information in conventional electrical and optical communication systems. Information is literally carried over long distances by the movement of these tiny particles in overground, underground and even subsea electrical and fibre-optic cables. Quantum communication takes advantage of quantum entanglement and teleportation, transferring matter or energy from one point to another without physically traversing the distance. Like conventional amplifiers at intermediate ‘nodes’ to reach long distances, quantum communication relies on quantum repeaters. Two concepts have emerged to realise quantum repeaters; however, they have not yet been investigated as a hybrid system combining the strengths of each. The EU-funded project QUREP has set out to do just that via combined theoretical and experimental studies, investigating for the first time an interconnected system of two disparate solid-state resources for quantum communication.

Objective

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.

Host institution

HUMBOLDT-UNIVERSITAET ZU BERLIN
Net EU contribution
€ 1 500 000,00
Address
UNTER DEN LINDEN 6
10117 Berlin
Germany

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Region
Berlin Berlin Berlin
Activity type
Higher or Secondary Education Establishments
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Total cost
€ 1 500 000,00

Beneficiaries (1)