Since 2016, the Charpak-Ritz price is jointly delivered by the Société Française de Physique and the Société Suisse de Physique to a physicist or a team for outstanding contributions to physics or its development.
The 2025 price is awarded to Nicolas Sangouard for his theoretical contributions to quantum optics and quantum information opening the way to groundbreaking experiments in quantum communication and computing.
With the background he learnt during his PhD at Université de Bourgogne on light-matter interaction, Nicolas Sangouard started in 2004, first at Kaiserslautern and then in Geneva, to work on efficient ways to store quantum light in atomic ensembles. He provided in particular rigorous descriptions of how single photons can be stored in solid-state systems and showed how experimentally accessible quantities influence the storage efficiency and fidelity.
These contributions paved the way for pioneer photon storage experiments in solid-state systems including the very first experiments reporting on entanglement between a photon and a solid-state atomic ensemble or between two solid-state atomic ensembles.
This led him to explore the applications of quantum memories in quantum communication from 2007. He proposed what are currently the most efficient architectures for realizing quantum networks with atomic-ensemble-based photon memories. These architectures, together with their accurate resource estimations, significantly contributed to the emergence of experimental activities on quantum networks, which is nowadays at the core of many national and international research programs. In 2014, Nicolas Sangouard joined some of these projects as he established an independent research group in Basel as a SNF professor. Through these projects, he developed theoretical models of light-matter interfaces with unprecedented precision, offering valuable support for experimental advancements in quantum networks across diverse physical platforms, including rare-earth-doped solids, diamond crystals, trapped ions, quantum dots, and superconducting qubits.
Starting from 2010, Nicolas Sangouard also investigated the applications of quantum networks for secure communications. After years of work, his group and him put together all the mathematical tools needed for making possible a demonstration of quantum key distribution with security guarantees independent of any assumptions on the internal functioning of devices used to produce the key. This led to the first and only experiment reporting on device-independent quantum key distribution.
Since 2019, Nicolas Sangouard is a CEA Senior Researcher at the Institut de Physique Théorique in Paris-Saclay. Together with his group, they highlighted the importance of integrating a quantum memory into quantum computing architectures. They demonstrated that this integration significantly reduces the number of processing qubits required to execute large-scale algorithms, achieving reductions by several orders of magnitude compared to standard architectures without quantum memory. This achievement could represent a pivotal step toward realizing the first large-scale quantum computer.