Philip Sibson

CHIP-BASED QUANTUM KEY DISTRIBUTION

Improvement in secure transmission of information is an urgent need for governments, corporations and individuals. Quantum key distribution (QKD) promises security based on the laws of physics and has rapidly grown from proof-of-concept to robust demonstrations and deployment of commercial systems. Despite these advances, QKD has not been widely adopted, and large-scale deployment will likely require chip-based devices for improved performance, miniaturization and enhanced functionality. Here we report low error rate, GHz clocked QKD operation of an indium phosphide transmitter chip and a silicon oxynitride receiver chip—monolithically integrated devices using components and manufacturing processes from the telecommunications industry. We use the reconfigurability of these devices to demonstrate three prominent QKD protocols—BB84, Coherent One Way and Differential Phase Shift—with performance comparable to state-of-the-art. These devices, when combined with integrated single photon detectors, pave the way for successfully integrating QKD into future telecommunications networks.

Secure NFV Orchestration Over an SDN-Controlled Optical Network With Time-Shared Quantum Key Distribution Resources

Quantum key distribution (QKD) is a state-of-the-art method of generating cryptographic keys by exchanging single photons. Measurements on the photons are constrained by the laws of quantum mechanics, and it is from this that the keys derive their security. Current public key encryption relies on mathematical problems that cannot be solved efficiently using present-day technologies; however, it is vulnerable to computational advances. In contrast QKD generates truly random keys secured against computational advances and more general attacks when implemented properly. On the other hand, networks are moving towards a process of softwarization with the main objective to reduce cost in both, the deployment and in the network maintenance. This process replaces traditional network functionalities (or even full network instances) typically performed in network devices to be located as software distributed across commodity data centers. Within this context, network function virtualization (NFV) is a new concept in which operations of current proprietary hardware appliances are decoupled and run as software instances. However, the security of NFV still needs to be addressed prior to deployment in the real world. In particular, virtual network function (VNF) distribution across data centers is a risk for network operators, as an eavesdropper could compromise not just virtualized services, but the whole infrastructure. We demonstrate, for the first time, a secure architectural solution for VNF distribution, combining NFV orchestration and QKD technology by scheduling an optical network using SDN. A time-shared approach is designed and presented as a cost-effective solution for practical deployment, showing the performance of different quantum links in a distributed environment.

A homodyne detector integrated onto a photonic chip for measuring quantum states and generating random numbers

We present the first silicon-integrated homodyne detector suitable for characterising quantum states of light travelling in a silicon waveguide. We report high-fidelity quantum state tomography of coherent states. The device was also used to generate random numbers at a speed of 1.2 Gbps.

Integrated photonic devices for quantum key distribution

We demonstrate a fully integrated photonic transmitter for time-bin based multi-protocol quantum key distribution. This GHz rate Indium Phosphide device prepares states for Coherent One Way (COW), Differential Phase Shift (DPS), and BB84 protocols.

Measurements towards providing security assurance for a chip-scale QKD system

Quantum key distribution (QKD) is one of the most commercially-advanced quantum optical technologies operating in the single-photon regime. The commercial success of this disruptive technology relies on customer trust. Network device manufacturers have to meet stringent standards in order to ensure the operational security of their devices. The National Physical Laboratory (NPL) and the University of Bristol (Bristol) are working to produce a suite of tests to determine the operating characteristics and implementation security of chip-scale quantum devices designed for security purposes. These tests will inform and provide assurance to potential customers of such devices. Results from initial measurements performed on the Bristol chip-scale transmitter and receiver are presented, with the aim of informing the development of the system.

An on-chip homodyne detector for generating random numbers

The homodyne detector is a primitive element in many quantum optics experiments. It is primarily a characterization device, used for measuring the quantum state of the electromagnetic field[1]. Quantum integrated photonics[2], in which optical sources, circuits, and detectors are monolithically integrated on a semi-conductor chip, provides a compact, scalable, platform in which to implement quantum devices like the homodyne detector.

Silicon quantum photonics

Silicon integrated quantum photonics has recently emerged as a promising approach to realising complex and compact quantum circuits, where entangled states of light are generated and manipulated on-chip to realise applications in sensing, communication and computation. Recent highlights include chip-to-chip quantum communications, programmable quantum circuits, chip-based quantum simulations and routes to scalable quantum information processing.