Quantum Communications

Practical implementation of quantum key distribution (QKD) is of vital importance to ensure the security of sensitive information and protection of critical infrastructure. Rapid advances in quantum computing will be a threat to existing encryption routines and leave all classical communication channels unprotected.

Quantum technologies allow us to encode information onto single photons, and QKD enables two parties to exchange a verifiably secure secret key, which can then be used to encrypt data. The fundamentals of QKD have been demonstrated in the lab, and Fraunhofer CAP is working with commercial partners to roll QKD out into real-world situations working towards quantum telecommunication networks.

QKD links through fibre and across ground-ground and space-ground links are essential for a complete network. Fraunhofer CAP is involved in the development of multiple free-space links for different use cases, including analysis of the effects of atmospheric turbulence, optical design work for terrestrial links and telescopes for small satellites, and fabrication of feedback and beam steering systems for active correction of turbulence and vibrations.

Photon sources and encoding schemes are another key element of a QKD link. Fraunhofer CAP has experience developing and testing a wide range of sources including weak-coherent pulse and entangled photon sources over different spectral bands. Source and systems are tested using state-of-the-art optical detection and characterisation equipment.

Key capabilities include:

• Free-space QKD links
• Optical and opto-mechanical design
• Atmospheric turbulence modelling
• Feedback control loops for active alignment
• Weak-coherent pulse sources
• High repetition rate sources
• Entangled photon sources
• High pair generation rate approaches
• Narrow-linewidth lasers and systems for continuous variable QKD

Next Generation Satellite QKD  -

Creating a UK Sovereign Capability for Manufacturing Satellite QKD Payloads   Quantum Key Distribution (QKD) facilitates the secure sharing of encryption keys using quantum technology. These keys can encrypt data for transmission over conventional fibre links across any distance, but QKD itself is limited over fibre to around 150km. Beyond this, 'trusted nodes' are required, but at major risk of creating security vulnerabilities. A number of fibre QKD networks are being built, including in the UK, but all are subject to this constraint. QKD through free space is less sensitive to distance. Thus, satellites provide the means for distributing keys across very large distances between end users spread across countries or continents - they are a facilitator of global QKD networks. Satellite components in QKD networks are being planned or researched in a number of countries. A consortium led by Arqit aims to establish the world's first commercial QKD satellite constellation. The first satellite is being build under contract with the European Space Agency, with a quantum payload being manufactured by European partners. There is an opportunity for the UK quantum technology industry to leapfrog other countries by creating a capability to manufacture the next generation of space QKD payloads here in the UK. The "Quantum Payload Factory" project will work with organisations across the UK to progress the state of the art of promising quantum communications technologies, understand their potential to enhance the performance of Arqit's global QKD system, validate their capabilities and technology readiness, engineer them to become "space ready" and develop an enhanced performance payload design that brings these new UK technologies into the second generation of Arqit satellites.

Fraunhofer CAP collaborated in this project with:

Arqit Ltd

AEGIQ LTD

BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY

Heriot-Watt University

NU QUANTUM LTD

ORCA Computing Ltd.

STFC - Laboratories

TOSHIBA EUROPE LIMITED

AIRQKD             

AirQKD establishes a UK ecosystem, from single-photon components to networked quantum systems, to protect short to mid-range communication in free space. In particular we carry out pilot demonstrations of the enabling infrastructure for quantum-secure 5G and autonomous and connected vehicles.

Fraunhofer CAP collaborated in this project with:

BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY

ANGOKA LIMITED

Arqit Ltd

BAY PHOTONICS LTD

Compound Semiconductor Applications Catapult Limited

Heriot-Watt University

NPL MANAGEMENT LIMITED

NU QUANTUM LTD

OPENLIGHTCOMM LTD

University of Bristol

University of Edinburgh

University of Strathclyde

University of Warwick

3QN: Towards A New UK Industry for Novel Quantum Receivers in Nascent Satellite QKD Global Markets        

Quantum Key Distribution (QKD) is a well understood application of quantum technology and there are several metropolitan fibre networks already established for QKD services. However, key distribution is limited by absorption inside optical fibres which mean that transmissions over distances greater than about 150 km are impractical. Free space communications, though, does not suffer the same degree of attenuation and single photon communication with satellites orbiting the Earth at several hundred kilometres has been demonstrated. Satellites then, provide an ideal vehicle for distributing quantum key information across very large distances between end users spread across countries or continents. However, in order to benefit from the advances in satellite technology, a network of Optical Ground Receivers (OGRs) are required to receive and detect the photons carrying the key information. The UK, as a major player in the development of advanced optical & photonic technologies, is well positioned to address this future market for OGR. This project works with users to specify OGR requirements and prototypes and tests a QKD receiver, whilst designing and making plans for scaled manufacture in the UK.

Fraunhofer CAP collaborated in this project with:

Arqit Ltd

BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY

HERIOT-WATT UNIVERSITY(THE)

NPL MANAGEMENT LIMITED

REDWAVE LABS LTD

Teledyne UK Limited

University of Cambridge

UNIVERSITY OF YORK

WIDEBLUE LIMITED