Magnetic atoms: from many-body physics to quantum technology

This project is aimed to investigate unique possibilities provided by systems of ultracold trapped large-spin magnetic atoms like Erbium or Dysprosium, to explore novel many-body quantum physics and to develop new quantum technologies. The long-range magnetic dipole-dipole interaction between the atoms drastically changes the nature of quantum degenerate regimes and leads to the emergence of new many-body states like, for example, supersolid that combines crystalline order with superfluidity, the property usually attributed to the fluid, not crystalline, phase. On the other hand, rich and highly controllable internal structure of intrinsically stable magnetic sublevels of these atoms in the electronic ground state allow going beyond the standard paradigm of two-level systems (qubits) in quantum computing and information processing in develop[ping and implementing schemes based on many-level systems (qudits). The project combines joint efforts of the leading theoretical and experimental groups in Austria (University of Innsbruck) and in Russian Federation (Russian Quantum Center in Moscow) and has a twofold objective: On the one hand, we plan to study both theoretically and experimentally novel many-body quantum states in systems of trapped ultracold gases of magnetic atoms. More specifically, we will study the supersolid state in a trapped dipolar gas of magnetic atoms for different trap geometries and develop and perform experiments showing the presence of both crystalline and superfluid orders. We will also consider dipolar systems with disorder, where we address the questions of the expected disorder-induced increase of the BCS transition temperature in a two-component gas of fermionic magnetic atoms to experimentally achievable values, and of the intriguing transition between ergodic and non-ergodic multifractal extended conducting states. On the other hand, we focus on the analysis of magnetic atoms as a potential platform for quantum computing and quantum information processing, and on developing corresponding experimental tools. In particular, we will investigate the possibility of using magnetic atoms as qudits many-level systems allowing encoding several qubits in one atom, and arrays of magnetic atoms in an optical lattice as a system of qudits. Such systems allow strong reduction of the number of physical elements and gate operations, as well as parallel processing in a single unit with lower error rates as compared to the qubits counterparts. We will also search for quantum algorithms which can most efficiently be accelerated using the qudit platform.

This project is devoted to systems of magnetic atoms - atoms which, due to their magnetic moments, interact with each other at much larger distances than nonmagnetic ones, and the strength of this interaction strongly depends on their magnetic moments orientation. Because of this, systems of magnetic atom are considered as a very promising platform for fundamental studies of many-body quantum phenomena and for developments of novel quantum technologies allowing designing, controlling, and manipulating quantum systems on the level of a single atom. We have studied, both experimentally and theoretically, several novel many-body quantum states and phenomena which are strongly connected or exist only due to the long-range dipole-dipole interactions between magnetic atoms. One of such states is the dipolar superfluid - an ensemble of magnetic atoms with the ability to flow without friction, with its very specific properties. Another is the most intriguing and mysterious state of matter - supersolid which combines a crystalline order (as a solid) with the ability of frictionless flow (as a superfluid), in the system of magnetic atoms. The above studies were accompanied by exact measurements of the magnetic atom properties, as well as development of optical tools for manipulating the internal quantum states of magnetic atoms - the first necessary steps towards engineering quantum devices.