[Romain Alléaume ] The first event was the School's move to the Palaiseau plateau, within the Institut Polytechnique de Paris, in 2020. Prior to this move, with the departure of the CNRS from the LTCI, the quantum team at Télécom Paris (then called IQA, Information Quantique et Applications) had lost three leading researchers. Fortunately, thanks to the very dynamic quantum ecosystem at Saclay, the success of the National Quantum Plan and the European Quantum Flagship, as well as the strengths and strong support of the School and the decisive backing of Inria, we were able to re-found a new team, called Quriosity (Quantum Information Processing and Communications Saclay), which will soon have five permanent members, and more than fifteen members in total.

The team's ambition is to further explore quantum information and computing, on the theoretical side, while at the same time taking an interest in the engineering of quantum systems and in particular complex systems, notably photonic systems.

[Romain Alléaume ] Within IP Paris, X and Télécom Paris are the most active members and have developed very strong links. Other relationships have also been strengthened with Institut d'Optique, ENS Paris Saclay and Université de Paris Saclay. One of the most striking examples is the ARTeQ training program, part of the Quantum-Saclay center, whose teachers include J-F Roch, A. Aspect (Nobel Prize 2022), Ph. Grangier, P. Senellart, P. Arrighi, J-D Pillet and others.

In 2022, IP Paris has also won a €28 million grant from the ANR's "d'ExcelllenceS" program, part of which is dedicated to the development of quantum sciences and technologies, in particular quantum computing, and will support the development of the Quriosity team at Télécom, within the LTCI laboratory.

[Romain Alléaume ] Since January 1, 2023, and after a process of elaborating a scientific project, the QURIOSITY team has been founded as a joint team between IP Paris and Inria. In addition to participating in Inria programs and the life of the institute, the project-team status enables the team to gain visibility and attract talent, which has resulted in two Inria recruitments in 2022 and 2023, while two other recruitments have taken place at Télécom Paris in 2021 and 2023.

[Romain Alléaume ] As far as quantum communications are concerned, we know how to use quantum technologies on optical fiber or satellite links, but it's tricky to deploy them on existing operational communications networks.

As part of the Paris Région QCI program, in partnership with Orange, a fiber optic network dedicated to quantum communications has been deployed in the Paris region. It links Paris Centre and Saclay, including a link between our Laboratory and Orange Labs in Chatillon.

While a quantum computer capable of solving practical problems is still some way off, being able to combine classical and quantum technologies looks very promising in terms of shorter-term applications. This is also true for quantum cryptography. For example, hybridization between quantum and computational cryptography - an avenue that we are exploring with great enthusiasm in the team, and which was unthinkable a few years ago by "the purists" - now appears to be a direction that, by seeking good models with classical computational assumptions, would enable us to scale up and significantly increase the surface area of possible use cases for secure quantum communications.

[Romain Alléaume] This computer would enable applications that are currently impossible to achieve with current technologies. For example, a polynomial algorithm for factoring does exist: it's the Shor algorithm discovered in 1994, whereas no such algorithm exists conventionally. However, a quantum computer capable of running Shor's algorithm to break current public-key cryptography (typically RSA 2048) is still a long way off, as it would require millions of qubits (considering current qubits, which are noisy).

However, other promising algorithms seem likely to be implemented before Shor's algorithm.

Many different technologies are currently being studied to create a quantum computer (superconducting qubits, trapped ions, neutral atoms, photonics, etc.). The main difficulty lies in the realization of a large number of physical qubits with low noise. It's a very complex problem to solve, but a very stimulating one indeed. A burning scientific frontier, and also a route to the realization of a large quantum computer, will involve the implementation of quantum error-correcting codes, and the ability to encode, on several physical qubits, a logical qubit which would then present a greatly reduced noise level compared with the physical qubits.

As part of the studies carried out at Quriosity, we are interested not only in error correction, but also in applications that can be realized with a few hundred or even a few thousand qubits.

[Romain Alléaume ] Yes, certainly. For example, let's suppose that the lifetime of an encryption system is at most one day. Today, it's impossible to store quantum information for that length of time (it's more like fractions of a second). Quantum Computational Timelock is the name we've given to the protocols that combine these hypotheses, and we've also shown that in this new framework, we can obtain quantum cryptographic protocols with greatly enhanced performance, while offering security that is classically unattainable.

[Romain Alléaume] The field of quantum technologies is booming, and offers career opportunities in both research and industry for engineers from the École, whether in large companies or start-ups such as Quandela and Pasqal, which are based in Massy and with which we have close links.

We play an active role in quantum education at the École, not only in the 1A and 2A programs, but also in the development of the Quantum Engineering specialization program in 3A, run in partnership with Quantum-Saclay, and in Telecom Executive Education's continuing education modules.

Our only relative difficulty is recruiting post-doctoral fellows, as financial conditions are lower than in other countries (e.g. Germany).