Quantum information processing with quantum-optical systems: from quantum networks to computation

Physics lies at the core of technological innovation. This can be understood by noting that scientific breakthroughs, i.e. revolutions in our understanding of nature, have typically been followed by historical periods of equally profound technological advances - an evident pattern across human history. Even through- out the very last centuries, extensive witnesses of this paradigm can be found. These include, for instance, the development of engines, which was propelled by new insights into thermodynamics and statistical physics. Similarly, landmark discoveries in electricity and electromagnetism paved the way for the advent of electric light. More recently, advancements in nuclear energy were made possible through a deeper understanding of atomic physics. These examples underscore how revolutions in physics set the groundwork for transformative technologies - as well as technological progress allows new discoveries, by providing scientists with more and more advanced experimental capabilities. At the frontier of this interplay between science and technology lays a rela- tively young field of research in physics, which is commonly referred to as quan- tum information. This discipline studies and exploits peculiar aspects of quantum theory, both of complex many-body systems and at the single-particle level, in tasks such as, e.g., computation and cryptography. Specifically, pioneering works in the ‘90s have found that quantum systems feature remarkably non-standard properties under the information-theoretical perspective; crucially, these features can be leveraged to obtain advantageous performances for specific tasks. Impor- tant examples include computations, where quantum processors allow tremen- dous speedups for solving certain problems, and communications, where quan- tum key-distribution (QKD) protocols unlock unprecedented levels of provable security. Altogether, this vision motivates impressive ongoing efforts in the real- ization of quantum technologies, from the development of quantum networks to the ambitious goal of building a quantum computer. Within this context, we will approach the interplay between fundamental physics, quantum information and quantum technologies from different perspec- tives. In some cases, we will use advanced tools in foundational quantum optics to enhance the performance of several quantum information processing tasks; this includes e.g. the protection of quantum states against losses in long-range quantum communications, as well as the employment of optimal control tech- niques to design robust quantum gates in neutral atom arrays. In other cases, we will use techniques borrowed from quantum information to provide novel un- derstandings of complex many-body quantum optical systems, such as ’globally- driven’ neutral atom arrays. As an example of convergence of these two ap- proaches in a unified picture, we will also present a completely novel model for quantum computation with quantum many-body systems composed by so-called Rydberg atoms.