Tensor Networks in Simulation of Quantum matter

• Applicants: Dr. Mari Carmen Bañuls; Privatdozent Dr. Karl Jansen
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas ; Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 499031220

In our Quantum Science era where fault-tolerant quantum devices are still not available but Noisy Intermediate-Scale Quantum (NISQ) devices are accessible, quantum information tools to guide their development plays a fundamental role. With the foreseen increasing complexity of available NISQ devices, their classical simulations - that drove their development until now - will soon fail to keep up. There is thus an urgent need for increasingly powerful diagnostic tools that can be applied to quantum devices even in the quantum advantage regime. We plan to systematically develop quantum-inspired algorithms to benchmark, certify and validate quantum devices. At the center of the quantum-inspired algorithms lay tensor networks (TN), one of the most powerful paradigms for simulating quantum many-body lattice systems, both in- and out-of-equilibrium, via a representation of the quantum state with tailored variational ansatz wave functions. The last years have seen impressive progress in TN algorithms, and in T-NiSQ we plan to bring these developments one step further, beyond the level of academic/proof-of-principle demonstrations, towards truly applicable tools for the modelling and design of quantum devices. In particular, we will develop benchmarking tools for high-dimensional quantum systems in the presence of noise, and we will test our algorithms in state-of-the-art quantum simulations and computations. The results of T-NiSQ will be an essential tool to advance our understanding of dynamical and strong- correlation effects in quantum matter also beyond the NISQ era. Our approach is only possible thanks to a collaborative effort between theory and experiment, and an interdisciplinary approach leveraging the combined expertise of researchers from atomic, molecular, and optical (AMO) quantum technologies (QTs), and high-energy physics. Fostering Europe’s long- standing role in the development of AMO-QTs, T-NiSQ brings together various key actors who will influence the future development of two of the European leading QTs: trapped ions and ultra-cold atoms. Cold atomic gases in optical lattices offer unprecedented opportunities for the manipulation and characterization of quantum phases of matter, and trapped ions are the leading platform for digital quantum information processing. T-NiSQ’s results will have applications ranging from condensed matter physics over high-energy physics to quantum information theory. Quantum simulators, quantum devices that replicate the behaviour of another quantum system, will also benefit from T-NiSQ results and will take advantage of facilitating the design of new materials, and even more efficient chemical reactions.

• DFG Programme: Research Grants
• International Connection: Austria, France, Italy, Slovenia, Spain
• Cooperation Partners: Professorin Dr. Zala Lenarcic; Professor Dr. Simone Montangero; Professor Dr. Enrique Rico Ortega; Professor Dr. Martin Ringbauer
• Co-Investigators: Professor Dr. Immanuel Bloch; Professor Dr. Juan Ignacio Cirac