Magnetic Atoms Quantum Simulators / QUANTERA CONSORTIUM MAQS

Members of the MAQS consortium include:

We propose a quantum simulator made of magnetic atoms in periodic potentials, which will enable the investigation of quantum-many body problems associated with long-range dipole-dipole interactions. We propose to develop a number of new tools to increase the strength of dipole-dipole interactions (shorter-period UV lattices, magneto-association of magnetic atoms into molecules with a stronger magnetic moment), and to control and measure their interaction at the nano-scale (using super-resolution techniques and narrow spectroscopic lines). Most importantly, we will develop new probes to certify the presence of quantum correlations, which are expected to be particularly strong in these many-body long-range interacting systems. Experimentally, we will either probe correlations in real space (microscope, double-well lattices), in momentum space (Doppler spectroscopy, time-of-flight), or in the spin sector. These probes will be developed in close collaboration with theory, to find the best ways to define and quantify entanglement.

Working towards these aims, our results so far include: (i) the construction of two new quantum gas microscope experiments to probe Er and Dy individually, or in a mixture combination. (ii) the experimental characterization of correlations by measuring collective spin fluctuations. (iii) a number of new proposals to characterize entanglement in large spin systems, such as: methods relevant for quantum gas microscopes; data-driven approaches to reconstruct optimal Bell inequalities and entanglement criteria tailored on the input of experiments, based on collective measurements; methods to retrieve higher-order correlations from single-shot images; methods to reveal entanglement in momentum space. A number of new numerical methods have been devised (time-dependent variational approach, time-dependent Schwinger-boson approach) or implemented (DMRG, exact diagonalization, BCS mean-field), which allowed to explore out-of-equilibrium dynamics, and a variety of models with long-range interactions such as the extended Bose-Hubbard model, long-range Kitaev chains, long-range XXZ model, or phonon modes in polarized magnetic atoms localized in an optical lattice.

These first achievements set us in a good way to complete our program, which is to show that lattice-trapped magnetic atoms can be used as quantum simulators, in order to investigate various families of problems. First, we our aim is to probe low energy phases, and second, out-of-equilibrium situations to investigate dynamics and quantum thermalization. Thanks to these improvements, a number of phases could now be within experimental reach, such as the supersolid or stripe phases, or peculiar phases of spin systems with long-range interactions. We will aim at protocols to certify the nature of the quantum correlations within these systems. Such correlations can be explored in four different complementary setups: 1) an Er lattice gas within a Dy bath (Innsbruck); strongly dipolar lattice gases made of either 2) Dy atoms in UV lattices (Stuttgart) or 3) Dy₂ molecules in standard lattices (Pisa/Florence), and 4) Cr atoms realizing lattice spin models (Paris).

More info on Quantera’s website