| Project Detail |
The behaviour of engineered quantum systems, to be used as platforms for quantum technologies, is governed to a great extent by the interaction with the surrounding environment, which may act as a disturbance or be used as a resource. Hence, the theory and modeling of open quantum systems has become a major field of studies over the last two decades. In an open quantum system, the interaction between the system and its surrounding environment may result in novel emergent phenomena. Dissipative critical phenomena have emerged in particular as a new class of critical phenomena, often defining new universality classes. Dissipative phase transitions have recently also been proposed as a way to improve the performance of several quantum technologies, particularly in quantum sensing and quantum computing. Open quantum systems offer a unique opportunity for preparing and manipulating systems in specific quantum states. Dissipative state engineering and stabilization are at the foundations of many applications, particularly in quantum computing with bosonic quantum error correction. Many-body, driven-dissipative quantum systems are often characterized by a high level of complexity resulting from the combined effects of the unitary dynamics brought by the laws of quantum mechanics and irreversible dissipative processes. The theory and modeling of these systems is therefore a thriving field of research. The complexity of open quantum systems also calls for advanced numerical methods for their simulation. Efficient numerical methods should take advantage of the specific features of the system being simulated, as well of the specific regime of operation, in order to provide effective and predictive descriptions at a reasonable computational cost.These considerations set the ground for the present project. We will investigate both fundamental and applied aspects of open quantum systems.One part of this project will lead to a significant improvement of the state-of-the-art of bosonic quantum codes, thanks to the conception and thorough investigation of two novel codes -- the squeezed cat code and the critical dissipative cat code. By leveraging dissipative state-space stabilization and dissipative phase transitions, and through the analysis of previously unexplored regions in the space of physical parameters, we will demonstrate optimal operation regimes and control protocols for bosonic quantum codes codes, in particular for one- and two-qubit gates and for qubit readout. Our results will open the way to the experimental realization of these improved codes, and ultimately to a significant progress along the path leading to fault-tolerant quantum computing.Another part of this project will address the fundamental topic of dissipative phase transitions and dissipative chaos in bosonic systems. We will investigate criteria for characterizing integrability and chaos in these systems, study the emergence of dissipative chaos as a dissipative phase transition in arrays of resonators with boundary drive and dissipation, and characterize its universal properties. We will also propose settings for observing dissipative chaos in superconducting circuit devices. These results will provide a unified picture of dissipative critical phenomena, thereby significantly advancing our knowledge of open quantum systems.In a third and overarching part of this proposal, building upon the Applicants experience in the development of modeling and numerical methods for open quantum systems, we will develop and implement a methodological framework for the simulation of open quantum systems, relying on assumptions that are typically verified in bosonic quantum codes, as well as in other systems invariant under discrete symmetries. This research will result in effective and predictive tools that will enable the modeling of multi-qubit bosonic architectures, so to develop optimal stabilization and control protocols, and pave the way to the first experimental demonstration of a fault-tolerant bosonic qubit architecture. |
