Raja Yehia | LIP6 - Équipe QI

Energetic Analysis of Emerging Quantum Communication Protocols

Mon, 06 Jan 2025 00:00:00 +0000

Energetic Analysis of Emerging Quantum Communication Protocols

Wed, 16 Oct 2024 00:00:00 +0000

With the rapid development and early industrialization of quantum technologies, it is of great inter- est to analyze their overall energy consumption before planning for their wide-scale deployments. The evaluation of the total energy requirements of quantum networks is a challenging task: different networks require very disparate techniques to create, distribute, manipulate, detect, and process quantum signals. This paper aims to lay the foundations of a framework to model the energy requirements of different quantum technologies and protocols applied to near-term quantum networks. Different figures of merit are discussed and a benchmark on the energy consumption of bipartite and multipartite network proto- cols is presented. An open-source software to estimate the energy consumption of photonic setups is also provided.

Connecting Quantum Cities: Simulation of a Satellite-Based Quantum Network

Mon, 01 Jul 2024 00:00:00 +0000

We present and analyse an architecture for a European-scale quantum network using satellite links to connect Quantum Cities, which are metropolitan quantum networks with minimal hardware requirements for the end users. Using NetSquid, a quantum network simulation tool based on discrete events, we assess and benchmark the performance of such a network linking distant locations in Europe in terms of quantum key distribution rates, considering realistic parameters for currently available or near-term technology. Our results highlight the key parameters and the limits of current satellite quantum communication links and can be used to assist the design of future missions. We also discuss the possibility of using high-altitude balloons as an alternative to satellites.

All graph state verification protocols are composably secure

Mon, 25 Mar 2024 00:00:00 +0000

Graph state verification protocols allow multiple parties to share a graph state while checking that the state is honestly prepared, even in the presence of malicious parties. Since graph states are the starting point of numerous quantum protocols, it is crucial to ensure that graph state verification protocols can safely be composed with other protocols, this property being known as composable security. Previous works [YDK21] conjectured that such a property could not be proven within the abstract cryptography framework: we disprove this conjecture by showing that all graph state verification protocols can be turned into a composably secure protocol with respect to the natural functionality for graph state preparation. Moreover, we show that any unchanged graph state verification protocols can also be considered as composably secure for a slightly different, yet useful, functionality. Finally, we show that these two results are optimal, in the sense that any such generic result, considering arbitrary black-box protocols, must either modify the protocol or consider a different functionality. Along the way, we show a protocol to generalize entanglement swapping to arbitrary graph states that might be of independent interest.

Quantum City: simulation of a practical near-term metropolitan quantum network

Mon, 14 Nov 2022 00:00:00 +0000

We present the architecture and analyze the applications of a metropolitan-scale quantum network that requires only limited hardware resources for end users. Using NetSquid, a quantum network simulation tool based on discrete events, we assess the performance of several quantum network protocols involving two or more users in various configurations in terms of topology, hardware and trust choices. Our analysis takes losses and errors into account and considers realistic parameters corresponding to present or near-term technology. Our results show that practical quantum-enhanced network functionalities are within reach today and can prepare the ground for further applications when more advanced technology becomes available.

Design and Optimization of Tools for the Quantum Internet

Mon, 24 Oct 2022 00:00:00 +0000

In this thesis, we explore different aspects of quantum networks to help the international community build the Quantum Internet. We define the Quantum Internet, show the main challenges and some applications. We study the state of the art of metropolitan quantum networking, by simulating bipartite and multipartite protocols in a realistic context. We also study the composable security of a verification protocol that is used as a building block by other protocols. Finally, we analyse the possibility of long-distance quantum communication, first by studying a series of quantum repeater protocols, then by simulating satellite communication. This thesis was written in the context of quantum Internet development. We try here to contribute to the community by discussing some security concerns and by providing detailed models and simulation studies of quantum internet architectures and protocols. We also try to give a comprehensive introduction to the quantum Internet that encompasses some of its most important aspects. It hopefully highlights important parameters and issues to resolve, while showing what could be realizable as of today.

Design and Optimization of Tools for the Quantum Internet

Mon, 24 Oct 2022 00:00:00 +0000

This thesis is written in the context of quantum Internet development. We try here to contribute to the community by discussing some security concerns and by providing detailed models and simulation studies of quantum internet architectures and protocols. We explore different aspects of quantum networks on the path to the Quantum Internet. After introducing basic quantum information notions, we define the Quantum Internet and highlight the main goals and challenges. Then, we list a few bipartite and multipartite applications. After that, we study the composable security of a multipartite entanglement verification protocol, that is used as a building block by many other protocols. In the following chapter, we perform simulations of different quantum repeater protocols allowing connection between two distant nodes. These repeaters use a defect in the crystalline structure of the diamond, that we model. Finally, the last two chapters are dedicated to building and simulating an international quantum network architecture that minimizes the necessary hardware for the end users. We first study a metropolitan network, called the Quantum City, that we simulate in a Parisian context. We highlight the main parameters and today’s performances. Then, we study the feasibility of connecting different quantum cities separated by hundred of kilometers using satellites.

Composable Security for Multipartite Entanglement Verification

Wed, 19 May 2021 00:00:00 +0000

We present a composably secure protocol allowing $n$ parties to test an entanglement generation resource controlled by a possibly dishonest party. The test consists only in local quantum operations and authenticated classical communication once a state is shared among them and provides composable security, namely it can be used as a secure subroutine by $n$ honest parties within larger communication protocols to test if a source is sharing quantum states that are at least $\epsilon$-close to the GHZ state. This claim comes on top of previous results on multipartite entanglement verification where the security was studied in the usual game-based model. Here, we improve the protocol to make it more suitable for practical use in a quantum network and we study its security in the Abstract Cryptography framework to highlight composability issues and avoid hidden assumptions. This framework is a top-to-bottom theory that makes explicit any piece of information that each component (party or resource) gets at every time-step of the protocol. Moreover any security proof, which amounts to showing indistinguishability between an ideal resource having the desired security properties (up to local simulation) and the concrete resource representing the protocol, is composable for free in this setting. This allows us to readily compose our basic protocol in order to create a composably secure multi-round protocol enabling honest parties to obtain a state close to a GHZ state or an abort signal, even in the presence of a noisy or malicious source. Our protocol can typically be used as a subroutine in a Quantum Internet, to securely share a GHZ state among the network before performing a communication or computation protocol.