ML4Q Concepts

Series #5: Quantum Communication

The fifth ML4Q Concepts seminar series on quantum communication is organized by Anne Matthies, PhD student from University of Cologne.

The seminars will be online, via zoom. The Zoom link will be sent via the cluster’s mailing lists. If you are not affiliated with ML4Q but would like to participate, please drop a line to the ML4Q office. Suggestions for topics/speaker for follow-up seminar series are always welcome via our (ML4Q-internal) Slack workspace!

Seminar schedule

10 November 2022, 11:00

Eleni Diamanti (CNRS, Sorbonne Université)


Communication in a quantum world

Quantum technologies have the potential to improve in an unprecedented way the security and efficiency of communications in network infrastructures. We discuss the current landscape in quantum communication and cryptography, and focus in particular on recent photonic implementations, using encoding in discrete or continuous properties of light, of central quantum network protocols, enabling for instance secret key distribution, verification of multiparty entanglement and transactions of quantum money, with security guarantees impossible to achieve with only classical resources. We also describe current challenges in this field and our efforts towards the miniaturization of the developed photonic systems, their integration into telecommunication network infrastructures, including with satellite links, as well as the practical demonstration of novel protocols featuring a quantum advantage for a wide range of tasks. These advances enrich the resources and applications of the emerging quantum networks that will play a central role in the context of future global-scale quantum-safe communications. 

24 November, 11:00

Markus Huber (IQOQI Vienna, ÖAW)


High-dimensional entanglement for quantum communication

Entanglement unlocks many applications in quantum communication, such as the highest possible level of security in quantum key distribution. As photons are inevitably lost or decohered over longer distances, it seems obvious that using the full spectrum of photonic degrees of freedom is desirable. In addition to more encodable bits per photon, entanglement in high dimensions also yields a surprising resistance to noise. This comes at the expense of more complicated measurements that in themselves can contribute to the overall noise in the data, leading to an interesting optimisation. While random, noisy entanglement may not always be useful or need unrealistic control to be harnessed, I will also present a protocol that can be used in high-dimensional systems, even with restricted measurement possibilities, which has recently been successfully employed in path and energy-time experiments.

1 December 2022, 16:00

Filip Rozpędek (University of Chicago)


Quantum Repeaters for Quantum Communication

Quantum channels enable the implementation of communication tasks inaccessible to their classical counterparts. The most famous example is the distribution of secret key. However, in the absence of quantum repeaters, the rate at which these tasks can be performed is dictated by the losses in the quantum channel. In practice, channel losses have limited the reach of quantum protocols to short distances. Quantum repeaters have the potential to significantly increase the rates and reach beyond the limits of direct transmission. This talk will provide a high-level overview of different types of the proposed quantum repeater architectures. We will then look at the specific techniques that these schemes utilise in order to achieve long distance quantum communication, analyse their strengths and limitations as well as discuss the required hardware needed to implement them. Finally, I will introduce a novel type of quantum repeater schemes which make efficient use of the quantum communication channels by encoding quantum information in the bosonic error-correcting codes.

15 December 2022, 11:00

Glaucia Murta (HHU Düsseldorf)


Device-independent quantum cryptography

In this talk I will introduce the device-independent framework, and explain how the violation of a Bell inequality can be used to certify the security of cryptographic protocols. I will discuss how device-independent cryptography leads to security even when the underlying system and measurement setups are not well characterized or provided by an untrustworthy provider. Finally I will comment on the theoretical and experimental challenges and the progress in implementing device-independent quantum key distribution.