Periodic Reporting for period 2 - RYSQ (Rydberg Quantum Simulators) Reporting period: 2016-09-01 to 2018-02-28 Summary of the context and overall objectives of the project The central objective of the RySQ project is to implement and exploit Quantum Simulators based on Rydberg atoms (called Rydberg Quantum Simulators, RQS), because their outstanding versatility allows us to address not just one but a whole family of quantum simulations, by exploiting different aspects of the same experimental and theoretical tools. Unique features of laser excited Rydberg atoms are their long-range van-der-Waals or dipolar interactions, which are simultaneously very large, and entirely controllable by external fields. They offer therefore many different modes of operation, with either single atom or collective variables, dissipative, monitored and coherent dynamics, short and long range interactions, qubits and multi-level systems. Therefore, RQS provide a powerful toolbox for designing many-body quantum systems for quantum simulation, and to study static and dynamical behaviors, effects of dissipation, transport phenomena, applied to exotic and elusive phases of matter, including frustrated phases, lattice gauge theories, and non-equilibrium dynamics. The specific, overarching objectives for the project RYSQ are the following: (A) to build and run experimental multi-purpose platforms for quantum simulations based on Rydberg atoms; this is an “enabling” objective, aiming at the design and implementation of specific tools. This has been done within the 3 work packages (WP) :WP 1 “Benchmarking and interfaces”WP 2 “New concepts and new platforms”WP 3 “Interaction control in quantum systems” (B) to exploit for the first time the power of Rydberg Quantum Simulators (RQS) in a range of important problems; this is an “enabled” objective, constituting the core outcome of the project. This has been done within the 3 work packages (WP) :WP 4 “Many-Body Structures and Phase Transitions”WP 5 “Quantum simulation of non-equilibrium systems”WP 6 “Quantum simulation of open systems” Basically all these overarching objectives have been reached, following the initial design of the project, and the main highlights are presented in the next section. The results have been published in 102 articles in international journals, including 32 in high-impact journals (Science, Nature, PRL, PRX). They have also been presented in more than 500 contributions to international conferences, including 400 invited talks. In addition, the work has been disseminated in broad audience through various activities such as exhibition, podcast participation, interviews and live events for a total of more than 40 interactions. The general subject of quantum technologies is currently very present is the media, and RySQ partners were often involved in informal contacts with journalists. More generally, Quantum Technologies (QT) are now a major issue at the European level, due to the launch of the QT flagship. The RySQ partners are strongly involved at all levels of the flagship, both in the structures and committees organizing the Strategic Research Agenda, and in the research projects themselves. It is therefore expected that RySQ will be one of seeds growing up in a full tree, for major societal societal impact in the framework of the QT flagship. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far All along the project the scientific work has been progressing along the directions defined in the six work packages (WP) quoted above, and listed again here :WP 1 “Benchmarking and interfaces”WP 2 “New concepts and new platforms”WP 3 “Interaction control in quantum systems”WP 4 “Many-Body Structures and Phase Transitions”WP 5 “Quantum simulation of non-equilibrium systems”WP 6 “Quantum simulation of open systems”The results in each of the WP during the whole project are presented in the full project report. The very large list of results covers basically all the initial objectives of the project, and confirm the worldwide leadership of several teams within the RySQ consortium. The exploitation and dissemination of the results have been firstly within the project itself, in order to allow the achievements of the objectives over the three years duration. Secondly it has been through the publications and media actions, already listed in the previous section. Thirdly, the results have provided the basis for new ideas and new projects which are now fully developing in the framework of the QT flagship, in order to come to full fruition. Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) Generally speaking, the results of RySQ represent significant advances beyond the present state of the art, bringing closer the prospects of realizing functional quantum simulators, which will facilitate development of new materials and devices and exploitation of quantum technologies for the benefit of the society. The immediate impact has been felt within in the consortium and the academic community, as new directions emerged during the project. In particular, the devised novel schemes to implementing and controlling spin-like interactions and collisional interactions through Rydberg-dressing of atomic and molecular states provide highly promising approaches to quantum simulations that are explored in experiments within the RySQ consortium, and stimulate substantial experimental efforts around the world. In this regard, the demonstration of Rydberg-dressing in an atomic lattice constitutes a major milestone at the current frontier of quantum simulations of spin systems. Another major achievement within RySQ is the full control of trapped Rydberg atoms in arrays of optical tweezers, allowing experimentalists to manipulate individually many tens of Rydberg atoms with prescribed interactions. More generally, the demonstration of fully controlled Ising type quantum magnetism observable on the level of single elementary spins in such arrays defines the current frontiers of research on artificial magnets. Furthermore, system sizes have been reached, which are beyond the reach of simulations on classical computers, readily enabling quantum simulations of tailored magnetic Hamiltonians. Bottom-up approaches starting with well-controlled systems consisting of few atoms and photons can be compared to top-down settings, in which the collective response of the system is investigated, e.g. by monitoring the collective spin of the system for Heisenberg-like spin Hamiltonians. Finally, the potential of driven non-equilibrium systems with controlled dissipation as a novel type of quantum simulator has been demonstrated, and illustrates the benefits due to the strong interactions between Rydberg states. ryqs-logo-v1-0.png
