EMPIR 14IND05: MIQC2

• Forschungsstelle: METAS
• Projektnummer: F-5117.30061

Schlüsselwörter (Englisch)

Quantum cryptography, quantum key distribution, single photon, quantum technology, entanglement

Kurzbeschreibung (Englisch)

Quantum Key Distribution (QKD) is essentially the generation of perfectly secure random keys between two parties that communicate by an open quantum channel. This enables the parties to establish a secret key from short pre-shared secret and public exchanges, something which has never been shown to be possible with classical, non-quantum means. With increasing amounts of data being transmitted and stored online, there is an increasing need to secure that data. Researchers in the field consider QKD as the only truly secure key distribution technology (except secret courier) since it is secured by the laws of physics. Interestingly, conventional asymmetrical cryptography, which is almost exclusively used for key distribution today, could be rendered insecure by the advent of extremely powerful computers, including quantum computers, or new mathematical insights.

Fibre and free-space QKD systems use real devices, which do not have the ideal characteristics envisaged by the initial QKD concept. This means that those practical systems can be vulnerable to one or more of the many quantum hacking attacks proposed and/or demonstrated. Counter-measures against these attacks have already been identified, but their effectiveness should be ensured by rigorous characterisation of the optical components – this will be addressed by the consortium.
Another approach against these attacks is represented by entanglement-based QKD techniques e.g. device-independent (DI) QKD, measurement-device-independent (MDI) QKD, etc. The development of entanglement characterisation and quantification techniques is essential in order to provide the metrological framework for next-generation (entanglement-based) QKD systems.

 This is a joint research project carried out in the framework of the European Metrology Programme for Innovation and Research (EMPIR) (see:http://www.euramet.org/research-innovation/empir/). The EMPIR initiative is co-funded by the European Unions's Horizon 2020 research and innovation programme and the participating states. METAS is one of the project partners in the Project.

Projektziele (Englisch)

The aim of this project is to accelerate the development and commercial success of QKD technologies. This presents a number of metrological challenges, which result from the current and predicted development and deployment trajectories of QKD technologies.
Following the considerations above, the key objectives addressed in this project are:

1. The development of efficient measurement techniques for characterisation of counter-measures to side-channel and Trojan-horse attacks in fibre-based QKD systems, and the realisation of pilot measurement comparisons to validate the techniques.
2. The development of dedicated calibration techniques for new high-speed single-photon detectors for fibre-based QKD
3. The development of measurement techniques for the characterisation of the components of free-space QKD systems for ground-air communication, and the realisation of pilot measurement comparisons to validate techniques developed.
4. The development of measurement techniques for characterising quantum states.
5. To provide two Best-Practice Guides, one on characterisation of counter-measures to side-channel and Trojan-horse attacks, and one on characterisation of components of free-space QKD Systems.
6. Contribute to impact - via contributions to international guidelines/standards and showcase examples of early uptake by end users

METAS contributes to the project with its expertise in fibre-optic metrology and characterisation.

Abstract (Englisch)

This project has had as its main objective to contribute to the development of quantum cryptography technologies, and to increase its reliability, in particular through the development of measurement techniques and validations of the principles and components used for the development of commercial quantum key distribution systems (QKD). METAS has been mainly involved in measurement method development activities enabling the traceable characterization of the most critical components used in such systems. Most of the work done by METAS is concentrated in WP 1 of the project. The following key results were achieved:

• An innovative system for measuring the spectral analysis of optical fiber components has been developed and validated. It allows traceable measurements of transmission losses and retro-reflection rates in a wavelength range of 750 nm to 1800 nm. This very large range makes it possible in particular to evaluate the behavior of optical fiber components used in telecommunications outside usual wavelengths, to be able to identify potential security flaws in the QKD systems.
• A variety of components, such as optical fiber attenuators, optical filters using different spectral selection principles, and circulators could be measured using this system. The results obtained were very conclusive and were able to highlight numerous flaws that could potentially endanger the security of QKD systems. It has been clearly demonstrated that many standard components developed for conventional optical fiber telecommunications are not suitable for QKD systems.
• The spectral response of PIN type photodiodes used for monitoring the QKD system has been calibrated thanks to an adaptation of our already existing measurement bench.
• A method allowing the characterization of photon counting detectors of SPAD (Single Photon Avalanche Photodiode) type has also been developed. Its purpose is to evaluate the possibility of bringing the detector out of its photon counting regime and to determine the optical power needed to reach this state. This effect must be characterized in detail, because it allows, in principle, a QKD system vulnerable to an external attack.

Overall results obtained in this project are consistent, see beyond the goals initially set.

Umsetzung und Anwendungen (Englisch)

The characterization methods developed in this project have clearly demonstrated the absolute necessity to test the QKD system components in a very thorough way. Our spectral measurement system is one of the only ones in the world to cover such a wide spectral range, and opens the door to the realization of new calibration services for a new field of activity in full expansion in Switzerland and internationally. The results obtained seem to have already awakened certain interests that are likely to materialize in the near future. The establishment of a European Metrology Network (EMN) related to quantum technologies, including our activities has also been accepted.