FermiTrap · Atom-by-Atom Quantum Control of Fermions in Arbitrary Potentials

Atom-by-Atom Quantum Control of Fermions in Arbitrary Potentials

Understanding quantum mechanical systems of many particles is one of the big challenges in physics, with implications for chemistry, material design, condensed matter and information processing. Experiments with ultracold atoms enable us to experimentally create, manipulate and probe quantum many-body systems. Such experiments serve as important benchmarks for theories and thus underpin our fundamental understanding of quantum mechanics. The technological developments associated with the experiments also enable new practical use cases and devices, for example in atomic clocks, quantum sensing, cryptography and information processing. Our overall goal is to further push the experimental control over quantum many-body systems and utilize this control to harness quantum effects for new materials, devices etc. The main result of the action is the development of novel methods to image and characterize quantum states on the single-particle level. By now, many groups have been successful in imaging quantum gases with single-particle resolution, typically in optical lattices. Such measurements come with significant technical difficulties and only give access to position ordering of the underlying particles - one obtains a snapshot of the instantaneous distribution of particles. For many physical phenomena, most notably superfluidity, it is not the positions but rather the velocities (or momenta) or the particles that encode the crucial information about the quantum state, which is lost with conventional imaging methods. Our new approach enables to image both the position as well as the velocity distribution of individual particles in a quantum state in a technically much more straightforward manner. This technique makes microscopic access to quantum states available to many more groups working in the field and gives new observables for quantum states of itinerant particles. In particular, we showed that it is possible to access the entanglement properties of the Fermi-Hubbard dimer through spin-resolved correlation measurements in momentum and position space. Our results fit within the broader framework of simulating quantum materials with ultracold atoms, where the microscopic ingredients are highly controlled and understood. Eventually, such approaches will lead to new materials and coherent control of their properties, which may for example be relevant for improved speed of information storage in memory.

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