Quantum communication networks

Project Information

QINTERNET

Grant agreement ID: 679924

DOI

10.3030/679924

Project closed

EC signature date 4 February 2016

Start date 1 March 2016

End date 28 February 2021

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 498 725,00

EU contribution

€ 1 498 725,00

Coordinated by

TECHNISCHE UNIVERSITEIT DELFT
Netherlands

Periodic Reporting for period 4 - QINTERNET (Quantum communication networks)

Reporting period: 2020-09-01 to 2021-02-28

Summary of the context and overall objectives of the project

The objective of this project is to advance the real world realization of quantum communication networks. The vision of large interconnected quantum networks - a Quantum Internet- is to provide fundamentally new internet technology by ultimately enabling quantum communication between any two points on earth. Such a Quantum Internet will – in synergy with the ‘classical’ internet that we have today - connect quantum processors in order to achieve unparalleled capabilities that are provably impossible using classical communication.

As with any radically new technology, it is hard to predict all uses of the future Quantum Internet, but several major applications have already been identified. One striking application of quantum communication is quantum key distribution (QKD), which allows two remote network nodes to generate an encryption key, enabling the exchange of secret information between any users connected to the Quantum Internet. The security of QKD is guaranteed by the fundamental laws of nature, and thus fully future proof even against any attacker possessing a large-scale quantum computer. Other promising known applications are clock synchronization, extending the baseline of telescopes, secure identification, achieving efficient agreement on distributed data, exponential savings in communication, quantum sensor networks, as well as secure access to remote quantum computers in the cloud. Central to all these applications is the ability to send quantum bits (qubits). Qubits are fundamentally different from classical bits. While a classical bit can take only two values, ’0’ and ’1’, a qubit can be in a superposition of being ’0’ and ’1’ at the same time.

This project advances quantum network technology in two crucial directions:

First, it develops new techniques and methods that show how quantum application protocols can be realized safely and correctly on real world quantum devices that are subject to imperfections and errors. These efforts enable to the real world implementation of such protocols, ultimately making them available to future end-users.

Second, it develops methods for routing quantum information to the right destination in the network. Quantum bits are very fragile and can presently not be stored for more than a few seconds. To design and scale future quantum networks it is therefore imperative to enable efficient routing decisions within the lifetime of the quantum bits.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Highlights that advance the real world realization of quantum application protocols include:

• The realization of a 3 node quantum network in collaboration with quantum hardware developers that provides a future real world testbed for application development (Science, 2021)
• The identification of application driven stages of quantum network development, which provide a guideline to further development and aim to bridge communication gaps between experiment realizing quantum hardware, and application protocol designers (Science, 2018). These stages are now referred to in research agenda’s around the world (EU, DOE, NSF).
• An analysis of two-party quantum cryptographic protocols against imperfections in so-called continuous variable quantum systems, which enabled a real world implementation (Nature Communications, 2018).
• Furthermore, the world’s first application level simulator for quantum network has been realized to allow a tool for software development for quantum networks that is compatible with hardware efforts pursued by collaborators (SimulaQron, http://www.simulaqron.org Paper in Quantum Science and Technology, 4(1), 2018. Also at FOSDEM 2019 to engage the open source community.

This platform has been used by several hackathons exploring application development, see e.g. the Pan-European Quantum Internet Hackathon hosted by RIPE NCC and Quantum Internet Alliance.

Highlights that advance methods for routing quantum information:

In order to find methods that can eventually be realized in the real world, the project has developed both high level methods to understand quantum network routing, but also collaborated closely with quantum hardware developers. This includes the development of novel abstractions to capture the peculiarities of quantum hardware devices.

The world’s first link layer protocol for quantum network provides a layer of abstraction on which routing protocols can be built in a way that they can be used on essentially all known physical quantum hardware platforms (ACM SIGCOMM 2019).

A matching network layer protocol (CoNEXT 2020) to enable long-distance quantum communication. (Patent application pending).

To find useful routing algorithms and to understand their performance using real world devices, the world’s first discrete event simulator for quantum networks (NetSquid) was developed. (http://www.netsquid.org Preprint https://arxiv.org/abs/2010.12535 Accepted in Nature Communications Physics).

In the domain of quantum network, we have also developed tools to assess the performance of a quantum link – specifically to measure its quantum capacity (Nature Communications, 2018).

A popular science account about the push for a quantum internet interviewing the grant recipient can be found in e.g. Scientific American.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project has achieved many “firsts” in the world, significantly advancing the state of the art. Next to highly technical and mathematical work, this also includes the introduction of new concepts and abstractions that form a bridge between the realities of quantum hardware, and the much more abstract world of computer science.

For example, the project developed the world’s first quantum link layer protocol that effectively turns a physics experiment building quantum hardware into a well-defined network service on which others can now build upon without knowledge of the underlying quantum devices.

Next to advancing the realization of specific quantum application protocols, the project has provided guidance by identifying stages of quantum network development. This classified applications by their difficulty as summarized in this popular science item.

The project has also researched a number of unique methods that are now available as tools for other researchers, such as NetSquid.

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